Exposure apparatus

ABSTRACT

An exposure apparatus arranged to project a radiation beam onto a target portion of a substrate, the exposure apparatus having: a first substrate holder configured to hold the substrate; a second substrate holder configured to hold the substrate; a sensor holder configured to hold a sensor and/or detector; a first measurement device having a first alignment system having an alignment sensor configured to measure positions of a substrate alignment mark on the substrate; a second measurement device having a second alignment system having a further alignment sensor configured to measure positions of the substrate alignment mark on the substrate; a first scale arranged on a lower surface of the first substrate holder; and a first encoder head arranged to cooperate with the first scale, the first encoder head located beneath the first alignment system and held by a stationary support.

CROSS REFERENCE TO RELATED APPLICATIONS

This is the U.S. national phase entry of PCT Patent Application No.PCT/EP2018/052211, which was filed on Jan. 30, 2018, which claimspriority of European patent application no. 17154551.0, which was filedon Feb. 3, 2017, claims priority of European patent application no.17169025.8, which was filed on May 2, 2017, claims priority of Europeanpatent application no. 17193990.3, which was filed on Sep. 29, 2017, andclaims priority of European patent application no. 17201092.8, which wasfiled on Nov. 10, 2017, and which are incorporated herein in theirentireties by reference.

FIELD OF THE INVENTION

The present invention relates to an exposure apparatus.

BACKGROUND ART

A lithographic apparatus is a machine that applies a desired patternonto a substrate, usually onto a target portion of the substrate. Alithographic apparatus can be used, for example, in the manufacture ofintegrated circuits (ICs). In that instance, a patterning device, whichis alternatively referred to as a mask or a reticle, may be used togenerate a circuit pattern to be formed on an individual layer of theIC. This pattern can be transferred onto a target portion (e.g.comprising part of, one, or several dies) on a substrate (e.g. a siliconwafer). Transfer of the pattern is typically via imaging onto a layer ofradiation-sensitive material (resist) provided on the substrate. Ingeneral, a single substrate will contain a network of adjacent targetportions that are successively patterned. Known lithographic apparatusinclude so-called steppers, in which each target portion is irradiatedby exposing an entire pattern onto the target portion at one time, andso-called scanners, in which each target portion is irradiated byscanning the pattern through a radiation beam in a given direction (the“scanning”-direction) while synchronously scanning the substrateparallel or anti-parallel to this direction. A lithographic apparatus,which applies a desired pattern onto a substrate by irradiating aradiation beam, is also called an exposure apparatus. An exposureapparatus may be a stepper or a scanner. It is also possible to transfera pattern from a patterning device to a substrate by imprinting thepattern onto the substrate. A lithographic apparatus, which applies adesired pattern onto a substrate by imprinting the pattern onto thesubstrate, may be called an imprint-type lithographic apparatus. Animprint-type lithographic apparatus that imprints an entire pattern ontoa target portion of the substrate at one time may be called animprint-type stepper.

There is a trend to reduce the production costs per IC. To reduce theproduction costs per IC, known lithographic apparatus have been designedto perform the exposure process, i.e., exposing a pattern on thesubstrate, as fast as possible and as often as possible. To have theexposure process as often as possible, a lithographic apparatus may havemultiple substrate stages, as disclosed in U.S. Pat. No. 5,677,758.While a substrate on one substrate stage is being exposed, a secondsubstrate is being loaded, unloaded, or aligned on a second substratestage. When the one substrate has been fully exposed, the exposureprocess is only briefly interrupted to move the one substrate stage awayfrom the projection system and move the other substrate stage below theprojection system. This way, only during the brief interruption, thelithographic apparatus is not performing the exposure process.

SUMMARY OF THE INVENTION

Despite the exposure process is interrupted only briefly, there is adesire to expose substrates to create IC's with a further reducedproduction cost per IC. In general, overall productivity of alithographic apparatus is improved when throughput and/or uptime isimproved. Good imaging quality of a pattern transferred onto a substrateis often required for manufacturing ICs. More accurate measurement of asubstrate enables better imaging quality; however, if a more accuratemeasurement of a substrate is achieved by making a measurement timelonger, the longer measurement time will deteriorate the overallproductivity. In other words, there can be a trade-off between theoverall productivity and the imaging quality in known lithographicapparatuses.

Such a trade-off is observed, e.g., during a wafer alignment operationconducted by the exposure apparatus described in the PCT-applicationpublication No. WO 2007/097466A1. The exposure apparatus, described inthis PCT publication, comprises a single wafer stage and a single waferalignment system that comprises five alignment sensors lined up on astraight line along a first direction (e.g., along the x-axis or thestepping direction). When a wafer alignment operation is conducted asdescribed in this PCT publication, the 16 alignment marks can bemeasured by the single (multi-sensor) wafer alignment system whilemoving the wafer stage only along a second direction, which is thedirection perpendicular to the first direction (e.g., along the y-axisor the scanning direction). When a wafer alignment operation isconducted differently in this configuration, however, a longermeasurement time can be necessary, e.g., in the following cases; 1) alarger number of alignment marks on a substrate needs to be measured forenabling a better imaging quality, and/or 2) at least one of thealignment marks on a substrate to be measured (e.g., one of the 16alignment marks) is not located within the detection area of any one ofthe five alignment sensors (i.e., located outside of the detection areaof the five alignment sensors); as a result, the wafer stage needs to bemoved not only along the second direction but also along the firstdirection (i.e., not only along the y-axis but also along the x-axis).

In general, in an exposure apparatus that comprises a single waferstage, the time spent (prior to exposure) on the wafer alignmentoperation is a pure overhead time and directly deteriorates thethroughput performance of the exposure apparatus. Even in an exposureapparatus that comprises two wafer stages and a single wafer alignmentsystem, in the case that the time spent on the wafer alignment operationis longer than the time spent on exposure, the throughput performancewill be deteriorated. In general, an overall productivity of an exposureapparatus is proportional to the throughput performance for a certainuptime performance. Hence, a trade-off between the overall productivityand the imaging quality is observed in an exposure apparatus thatcomprises a single wafer stage and a single wafer alignment system.Also, there can be a trade-off between the overall productivity and theimaging quality in an exposure apparatus that comprises two wafer stagesand a single wafer alignment system in the case that a large number ofalignment marks on a substrate needs to be measured in order to qualifyfor a certain high imaging quality requirement.

Therefore, it is desirable, for example, to provide a lithographicapparatus in which better imaging quality can be achieved withoutdeteriorating the overall productivity. In other words, it is desirable,for example, to provide a lithographic apparatus in which better overallproductivity can be achieved while simultaneously qualifying for asufficient imaging quality required for manufacturing ICs.

Additionally or alternatively, it is desirable, for example, to providea lithographic apparatus that is flexibly and efficiently compatiblewith different substrate sizes since the desirable or availablesubstrate size can be different depending on the types of ICs to bemanufactured. Additionally or alternatively, it is desirable, forexample, to provide a lithographic apparatus that is flexibly andefficiently compatible with different types of substrates that are madeof different materials since the desirable or available types ofsubstrates can be different depending on the types of ICs to bemanufactured.

Additionally or alternatively, it is desirable, for example, to providea lithographic apparatus that is more inexpensive (i.e., at a lower toolprice) while simultaneously qualifying for a sufficient overallproductivity and a sufficient imaging quality required for manufacturinga certain type of ICs. In other words, there can be a trade-off betweenan overall productivity of an exposure apparatus and the tool price ofthe exposure apparatus. Therefore, it is desirable, for example, toprovide a lithographic apparatus that improves the CoO (Cost ofOwnership) while simultaneously qualifying for a sufficient overallproductivity and a sufficient imaging quality required for manufacturinga certain type of ICs. A contribution of a lithographic apparatus to theCoO may be estimated, e.g., as disclosed in Proc. of SPIE Vol. 5751, pp.964-975 (2005) or Proc. of SPIE Vol. 7271 72710Y (2009). Thesepublications may also be recognized as examples of the CoO calculationsfor different imaging quality requirements (e.g., for the 90 nm node andfor the 22 nm node, respectively).

Additionally or alternatively, in practice, multiple exposureapparatuses and some other types of apparatuses are usually necessaryfor manufacturing ICs. Hence, it is desirable to improve a TCO (TotalCost of Ownership) of multiple exposure apparatuses and/or a TCO of alltypes of apparatuses and processes required for manufacturing ICs.

In other words, there can be a trilemma between an overall productivity,an imaging quality and economy (which may, e.g., be recognized in termsof a footprint, a tool price, a CoO and/or a TCO) of an exposureapparatus. In this context, in addition to various trade-offs describedabove, there can be a trade-off between an overall productivity of anexposure apparatus and the footprint (and/or the tool price) of theexposure apparatus. For example, an exposure apparatus, described in thePCT-application publication No. WO 2007/055237A1, comprises twoillumination systems, two mask stages, two projection systems and twosubstrate stages. The tool price and footprint of such an exposureapparatus would be similar to two units of a conventional exposureapparatus, comprising a single illumination system, a single mask stage,a single projection system and a single substrate stage; furthermore, asthe number of optical components (such as an illumination system and aprojection system) is doubled, various problems of these opticalcomponents that can deteriorate the imaging quality would also bedoubled. In other words, a trade-off between the overall productivityand the imaging quality would still be observed in such an exposureapparatus, which is equivalent or similar to concatenating multipleunits of the conventional exposure apparatus. Therefore, such anexposure apparatus would not be economical and would not be a solutionto the trilemma between the overall productivity, the imaging qualityand the economy of an exposure apparatus.

According to an aspect of the invention, there is provided an exposureapparatus comprising a substrate holder, a sensor holder and a mover.The substrate holder is for holding a substrate. The sensor holder isfor holding a sensor. The mover is arranged for moving the substrateholder. The mover is arranged to couple with the sensor holder in afirst situation so as to move the sensor holder. The mover is arrangedto decouple from the sensor holder in a second situation so as to movewithout moving the sensor holder.

According to a further aspect of the invention, there is provided anexposure apparatus comprising a substrate holder for holding asubstrate, a sensor holder for holding a sensor, a mover arranged formoving the substrate holder, and a projection system arranged to providea beam of radiation onto the substrate. During exposure, the projectionsystem provides the beam of radiation onto the substrate when the sensorholder is decoupled from the mover. The mover couples with the sensorholder when the sensor measures a property of the projection system orthe radiation beam.

According to another aspect of the invention, there is provided anexposure apparatus comprising a first substrate holder for holding afirst substrate, a second substrate holder for holding a secondsubstrate, a projection system for exposing the first substrate with anexposure beam, a measurement device arranged to provide measurementinformation of the second substrate, and a further measurement devicearranged to provide measurement information of the first substrate. Thefurther measurement device is closer to the projection system than themeasurement device.

According to yet another aspect of the invention, there is provided anexposure apparatus comprising a first substrate holder configured tohold a substrate, a second substrate holder configured to hold thesubstrate, a sensor holder configured to hold a sensor, a projectionsystem configured to expose the substrate with an exposure beam, ameasurement device configured to provide measurement information of thesubstrate, a further measurement device configured to provide furthermeasurement information of the substrate. The sensor is configured tomeasure a property of the exposure beam and/or the projection system.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention will now be described, by way of exampleonly, with reference to the accompanying schematic drawings in whichcorresponding reference symbols indicate corresponding parts, and inwhich:

FIG. 1 depicts an embodiment according the invention;

FIG. 2 depicts a further embodiment according the invention in a firstview (e.g., in a top view);

FIG. 3 depicts the further embodiment according the invention in asecond view (e.g., in a side view);

FIG. 4 depicts an exposure apparatus according to the invention in afirst situation;

FIG. 5 depicts the exposure apparatus according to the invention in asecond situation;

FIG. 6 depicts the exposure apparatus according to the invention in athird situation;

FIG. 7 depicts yet a further embodiment according to the invention;

FIG. 8 depicts another embodiment according to the invention.

FIG. 9 depicts yet another embodiment according to the invention in aside view.

FIGS. 10A-10I depict a way of operating the embodiment of FIG. 9 in topviews.

DETAILED DESCRIPTION

FIG. 1 schematically depicts a lithographic apparatus according to oneembodiment of the invention. The lithographic apparatus comprises anillumination system IL, a support structure MT, a substrate table WT anda projection system PS. The illumination system IL is configured tocondition a radiation beam B. The support structure MT is constructed tosupport a patterning device MA and is connected to a first positioningdevice PM configured to accurately position the patterning device MA inaccordance with certain parameters. The substrate table WT isconstructed to hold a substrate W, e.g., a resist-coated wafer, and isconnected to a second positioner PW configured to accurately positionthe substrate W in accordance with certain parameters. The projectionsystem PS is configured to project a pattern imparted to the radiationbeam B by patterning device MA onto a target portion C (e.g. comprisingone or more dies) of the substrate W.

The illumination system IL may include various types of opticalcomponents, such as refractive, reflective, magnetic, electromagnetic,electrostatic or other types of optical components, or any combinationthereof, for directing, shaping, or controlling radiation.

The illumination system IL receives the radiation beam B from aradiation source SO. The radiation source SO and the lithographicapparatus may be separate entities, for example when the radiationsource SO is an excimer laser. In such cases, the radiation source SO isnot considered to form part of the lithographic apparatus and theradiation beam B is passed from the radiation source SO to theillumination system IL with the aid of a beam delivery system BDcomprising, for example, suitable directing mirrors and/or a beamexpander. In other cases the radiation source SO may be an integral partof the lithographic apparatus, for example when the radiation source SOis a mercury lamp. The radiation source SO and the illumination systemIL, together with the beam delivery system BD if required, may bereferred to as a radiation system.

The illumination system IL may comprise an adjuster AD for adjusting theangular intensity distribution of the radiation beam. Generally, atleast the outer and/or inner radial extent (commonly referred to asσ-outer and σ-inner, respectively) of the intensity distribution in apupil plane of the illumination system IL can be adjusted. In addition,the illumination system IL may comprise various other components, suchas an integrator IN and a condenser CO. The illumination system IL maybe used to condition the radiation beam B, to have a desired uniformityand intensity distribution in its cross-section.

The term “radiation beam” used herein encompasses all types ofelectromagnetic radiation, including ultraviolet (UV) radiation (e.g.having a wavelength of or about 365, 355, 248, 193, 157 or 126 nm) andextreme ultra-violet (EUV) radiation (e.g. having a wavelength in therange of 5-20 nm, or having a wavelength of or about 13.5 nm or 6.7 nm),as well as particle beams, such as ion beams or electron beams. Theradiation beam may comprise visible light, such as the spectral linesprovided by a Mercury lamp; a g-line (having a wavelength of or about436 nm) and/or an h-line (having a wavelength of or about 405 nm). Thevisible light may be provided by a single LED (light-emitting diode) ora combination of multiple LEDs. A single LED or a combination ofmultiple LEDs may provide UV radiation, visible light and/or infraredradiation.

The support structure MT supports, i.e. bears the weight of, thepatterning device MA. The support structure MT holds the patterningdevice MA in a manner that depends on the orientation of the patterningdevice MA, the design of the lithographic apparatus, and otherconditions, such as for example whether or not the patterning device MAis held in a vacuum environment. The support structure MT can usemechanical, vacuum, electrostatic or other clamping techniques to holdthe patterning device MA. The support structure MT may be a frame or atable, for example, which may be fixed or movable as required. Thesupport structure MT may ensure that the patterning device MA is at adesired position, for example with respect to the projection system PS.Additionally, the support structure MT may comprise a patterning deviceholder, a mechanism and/or a stage body that enable to actively bend thepatterning device MA. By actively bending the patterning device MA, acurvature of the patterning device MA may be controlled. Such a supportstructure MT is disclosed in the US patent applications publication No.US 2013/0250271A1 and US 2016/0011525A1, hereby incorporated byreference.

The term “patterning device” used herein should be broadly interpretedas referring to any device that can be used to impart a radiation beamwith a pattern in its cross-section such as to create a pattern in atarget portion C of the substrate W. It should be noted that the patternimparted to the radiation beam B may not exactly correspond to thedesired pattern in the target portion C of the substrate W, for exampleif the pattern includes phase-shifting features or so called assistfeatures. Generally, the pattern imparted to the radiation beam B willcorrespond to a particular functional layer in a device being created inthe target portion C, such as an integrated circuit.

The patterning device MA may be transmissive or reflective. Examples ofpatterning devices include masks, programmable mirror arrays, andprogrammable LCD panels. The patterning device MA may be referred to asa mask or a reticle. Optical properties of an aerial image (i.e., anaerial image of a pattern projected onto the substrate W) may becontrolled by actively bending a transmissive mask, a transmissivereticle, or a reflective mask. Masks are well known in lithography, andinclude mask types such as binary, alternating phase-shift, andattenuated phase-shift, as well as various hybrid mask types. An exampleof a programmable mirror array employs a matrix arrangement of smallmirrors, each of which can be individually tilted so as to reflect anincoming radiation beam in different directions. The tilted mirrorsimpart a pattern in the radiation beam B which is reflected by themirror matrix.

The term “projection system” used herein should be broadly interpretedas encompassing any type of projection system, including refractive,reflective, catadioptric, magnetic, electromagnetic and electrostaticoptical systems, or any combination thereof, as appropriate for theexposure radiation being used, or for other factors such as the use ofan immersion liquid or the use of a vacuum.

As here depicted, the lithographic apparatus is of a transmissive type(e.g. employing a transmissive mask). Alternatively, the lithographicapparatus may be of a reflective type (e.g. employing a programmablemirror array of a type as referred to above, or employing a reflectivemask).

The lithographic apparatus may be of a type having two (dual stage) ormore substrate tables (and/or two or more mask tables). In such“multiple stage” machines the additional tables may be used in parallel,or preparatory steps may be carried out on one or more tables while oneor more other tables are being used for exposure. An additional tablemay be arranged to hold at least one sensor, instead of holding asubstrate W. The at least one sensor may be a sensor to measure aproperty of the projection system PS, or a sensor to measure a propertyof the exposure radiation, a sensor to detect a position of a marker onthe patterning device MA relative to the sensor or may be any other typeof sensor. The additional table may comprise a cleaning device, forexample for cleaning part of the projection system PS or any other partof the lithographic apparatus.

The lithographic apparatus may also be of a type wherein at least aportion of the substrate W may be covered by a liquid having arelatively high refractive index, e.g. water, so as to fill a spacebetween the projection system PS and the substrate W. An immersionliquid may also be applied to other spaces in the lithographicapparatus, for example, between the patterning device MA and theprojection system PS. Immersion techniques are well known in the art forincreasing the numerical aperture of projection systems. The term“immersion” as used herein does not mean that a structure, such as asubstrate W, must be submerged in liquid, but rather only means thatliquid is located between the projection system PS and the substrate Wduring exposure.

The radiation beam B is incident on the patterning device MA, which isheld on the support structure MT, and is patterned by the patterningdevice MA. Having traversed the support structure MT, the radiation beamB passes through the projection system PS, which focuses the beam onto atarget portion C of the substrate W. The radiation beam B, which is usedfor exposing the substrate W, may also be referred to as an exposurebeam. With the aid of the second positioner PW and position sensor IF(e.g. an interferometric device, linear encoder or capacitive sensor),the substrate table WT can be moved accurately, e.g. so as to positiondifferent target portions C in the path of the radiation beam B.Similarly, the first positioner PM and another position sensor (which isnot explicitly depicted in FIG. 1) can be used to accurately positionthe patterning device MA with respect to the path of the radiation beamB, e.g. after mechanical retrieval from a mask library, or during ascan. In general, movement of the support structure MT may be realizedwith the aid of a long-stroke module and a short-stroke module, whichform part of the first positioner PM. The long-stroke module providesmovement of the support structure MT over a large range with limitedaccuracy (coarse positioning), whereas the short-stroke module providesmovement of the support structure MT relative to the long-stroke moduleover a small range with high accuracy (fine positioning). Similarly,movement of the substrate table WT may be realized using a long-strokemodule and a short-stroke module, which form part of the secondpositioner PW. In the case of a stepper (as opposed to a scanner) thesupport structure MT may be connected to a short-stroke actuator only,or may be fixed.

Patterning device MA and substrate W may be aligned using mask alignmentmarks M1, M2 and substrate alignment marks P1, P2. Although thesubstrate alignment marks P1, P2 as illustrated occupy dedicated targetportions, they may be located in spaces between target portions C.Substrate alignment marks P1, P2 are known as scribe-lane alignmentmarks, when they are located in spaces between the target portions C.Similarly, in situations in which more than one die is provided on thepatterning device MA, the mask alignment marks M1, M2 may be locatedbetween the dies.

The depicted apparatus could be used in at least one of the followingmodes:

In a first mode, the step mode, the support structure MT and thesubstrate table WT are kept essentially stationary, while an entirepattern imparted to the radiation beam B is projected onto a targetportion C at one time (i.e. a single static exposure). The substratetable WT is then shifted in the X and/or Y direction so that a differenttarget portion C can be exposed. In step mode, the maximum size of theexposure field limits the size of the target portion C imaged in asingle static exposure.

In a second mode, the scan mode, the support structure MT and thesubstrate table WT are scanned synchronously while a pattern imparted tothe radiation beam B is projected onto a target portion C (i.e. a singledynamic exposure). The velocity and direction of the substrate table WTrelative to the support structure MT may be determined by the(de-)magnification and image reversal characteristics of the projectionsystem PS. In scan mode, the maximum size of the exposure field limitsthe width (in the non-scanning direction) of the target portion C in asingle dynamic exposure, whereas the length of the scanning motiondetermines the height (in the scanning direction) of the target portionC.

In a third mode, the support structure MT is kept essentially stationaryholding a programmable patterning device MA, and the substrate table WTis moved or scanned while a pattern imparted to the radiation beam B isprojected onto a target portion C. In this mode, generally a pulsedradiation source is employed and the programmable patterning device MAis updated as required after each movement of the substrate table WT orin between successive radiation pulses during a scan. This mode ofoperation can be readily applied to maskless lithography that utilizesprogrammable patterning device, such as a programmable mirror array of atype as referred to above. This mode of operation can also be readilyapplied to e-beam (electron beam) lithography.

The lithographic apparatus further includes a control unit whichcontrols the actuators and sensors described. The control unit alsoincludes signal processing and data processing capacity to implementdesired calculations relevant to the operation of the lithographicapparatus. In practice, the control unit will be realized as a system ofmany sub-units. Each sub-unit may handle the real-time data acquisition,processing and/or control of component within the lithographicapparatus. For example, one sub-unit may be dedicated to servo controlof the second positioner PW. Separate sub-units may handle theshort-stroke module and the long-stroke module, or different axes.Another sub-unit may be dedicated to the readout of the position sensorIF. Overall control of the lithographic apparatus may be controlled by acentral processing unit, communicating with the sub-units, withoperators and with other apparatuses involved in the lithographicmanufacturing process.

Combinations and/or variations on the above described modes of use orentirely different modes of use may also be employed.

The substrate W may be any one of the following substrates: a silicon(Si) wafer, a Silicon-Carbide (SiC) wafer, a Sapphire wafer, a GalliumNitride (GaN) wafer, a GaN-on-Si wafer which is a silicon wafer with GaNlayers, a Gallium Phosphide (GaP) wafer, a Gallium Antimonide (GaSb)wafer, a Germanium (GE) wafer, a Lithium Tantalate (LiTa) wafer, aLithium Niobate (LiN) wafer, an Indium Arsenide (InAs) wafer, a IndiumPhosphide (InP) wafer or a glass substrate. The substrate W may be madeof any other materials such as Gallium Oxide and Gallium Arsenide. Asubstrate made of one of these materials may be more suitable than theothers for the production of a specific type of ICs. The substrate W mayhave any suitable size for the production of IC's, for example, adiameter of 12.5 mm or 50 mm or 100 mm or 150 mm or 200 mm or 300 mm or450 mm. The substrate W may have any suitable shape; e.g., the substrateW may be circular, square, or rectangular. The substrate W may have anysuitable size for the production of a mask, a template, a reticle, atest reticle or a dummy reticle, e.g., 6 inches square (6 inches×6inches). The substrate W may have any suitable size for the productionof flat-panel-displays (FPD), for example, G4, G6 (e.g., a size ofapproximately 1.5 m×1.8 m), G8 (e.g., a size of approximately 2.2 m×2.5m) or G10, etc. Multiple substrates may be contained in a FOUP (FrontOpening Unified Pod); e.g., 25 silicon wafers may be contained in aFOUP. These wafers may be referred to as a lot of wafers. A substratecontained in a first FOUP may be referred to as a substrate in a firstlot.

The lithographic apparatus of FIG. 1 is an example of an exposureapparatus. An exposure apparatus is an apparatus that provides anexposure device to expose a substrate W with an exposure beam, i.e.,radiation beam B. By exposing the substrate W, a pattern is created onthe substrate W. In case the exposure apparatus is an opticallithographic apparatus, the exposure device is usually referred to as aprojection system PS. In an embodiment, the projection system PScomprises a lens barrel and multiple optical elements (such as lenses,prisms and/or mirrors). In an embodiment, the projection system PSfurther comprises a lens holder for holding each optical element andactuators (such as piezo-elements) for controlling the position (e.g.,position in the vertical direction, i.e., along the z-axis) andorientation (e.g., tilting in the Rx- and Ry-directions). Examples of aprojection system PS, which can be used in the context of the invention,are disclosed in the PCT-application publications No. WO 2005/001543A1,WO 2005/064382A1 and WO 2007/091463A1, hereby incorporated by reference.

Another example of an exposure apparatus is an e-beam apparatus. Unlikean optical lithographic apparatus, the e-beam apparatus has an exposuredevice that provides an e-beam (electron beam) to the substrate W tocreate patterns on the substrate W. Such an exposure device may bereferred to as a modulation device. An e-beam may comprise a beam ofelectrons. The e-beam apparatus may be arranged to provide multiplee-beams simultaneously, by having multiple exposure devices or by havinga single exposure device arranged to provide multiple e-beamssimultaneously. An example of a modulation device, which can be used inthe context of this embodiment, is disclosed in Japanese patentapplication publication No. JP 2011-258842A, hereby incorporated byreference.

FIG. 2 depicts a first embodiment of the invention in a first view,e.g., in a top view. FIG. 3 depicts the first embodiment of theinvention in a second view, e.g., in a side view. FIGS. 2 and 3 showpart of an exposure apparatus 200 comprising a substrate holder 202, asensor holder 206 and a mover 204. The substrate holder 202 is arrangedto hold the substrate W. The sensor holder 206 is arranged to hold asensor. The mover 204 is arranged to move the substrate holder 202. Thesubstrate holder 202 may alternatively be referred to as ‘substratechuck’ or ‘wafer chuck’.

The mover 204 is arranged to move the substrate holder 202 relative tothe projection system PS, so the exposure beam projected from theprojection system PS can exposure ail target portions C. The mover 204may move in the x-direction, the y-direction and z-direction. The mover204 and/or the substrate holder 202 may be provided with an actuatorsystem for moving the substrate holder 202 relative to the mover 204while the mover 204 supports the substrate holder 202. The mover 204 maybe considered a long-stroke module for inaccurate movement over a largerange. The substrate holder 202 may be considered a short-stroke modulefor accurate movement over a small range. The substrate holder 202 maysupport the substrate table WT or may be integrated with the substratetable WT. The mover 204 may be provided with a planar motor to moverelative to the exposure device, e.g., projection system PS. The mover204 may be arranged to move relative to the projection system PS in thescanning direction, e.g., the y-direction as indicated in FIG. 2. Themover 204 may be arranged to move relative to the projection system PSin a direction perpendicular to the scanning direction, e.g., thex-direction as indicated in FIG. 2. The direction perpendicular to thescanning direction may be referred to as the stepping direction. Themover 204 may move in the scanning direction while the substrate W isbeing exposed by the projection system PS. The mover 204 may move in thestepping direction while the substrate W is not being exposed by theprojection system PS. The mover 204 may be arranged to move with ahigher acceleration and/or velocity in one of the scanning direction andthe stepping direction than in the other of the scanning direction andthe stepping direction. The planar motor may have magnets on the mover204 and coils on a base supporting the mover 204. Such a planar motormay be referred to as ‘moving magnet type planar motor’. Alternatively,the planar motor has the coils on the mover 204 and the magnets on thebase supporting the mover 204. Such a planar motor may be referred to as‘moving coil type planar motor’. Alternatively, the mover 204 maycomprise one linear motor or multiple linear motors. Additionally oralternatively, the mover 204 may be arranged in an H-drive-arrangement;in other words, the mover 204 may comprise at least one X-linear motor(i.e., a linear motor configured to primarily move in the x-direction)and at least one Y-linear motor (i.e., a linear motor configured toprimarily move in the y-direction). For example, the mover 204 arrangedin an H-drive-arrangement may comprise a pair of Y-linear motors and anX-linear motor, whose stator is attached to the moving parts of the pairof Y-linear motors.

The sensor holder 206 holds at least one sensor. For example, the sensorholder 206 has one sensor, or the sensor holder 206 has multiplesensors. The sensor may be a sensor to measure a property of theexposure beam, such as dose or aberrations or uniformity. The sensorholder 206 may comprise the additional table to hold the sensor or maybe integrated with the additional table. The sensor holder 206 maycomprise a cleaning device, for example for cleaning part of theprojection system PS or any other part of the lithographic apparatus.The sensor may comprise an aerial image measuring device configured tomeasure an aerial image of a pattern projected by the projection systemPS.

In an embodiment the sensor holder 206 is provided with at least one ofa sensor and a cleaning device. The sensor may be called a measurementmember. In an embodiment the sensor holder 206 is provided with anilluminance irregularity sensor. The illuminance irregularity sensor isconfigured to detect irregularity of illuminance of the radiation beam Bthat is received at a pin-hole shaped light-receiving section of theilluminance irregularity sensor. In an embodiment the sensor holder 206is provided with a sensor such as an aerial image measuring device. Theaerial image measuring device is configured to measure an aerial imageof a pattern projected by the projection system PS. In an embodiment thesensor holder 206 is provided with a sensor such as a wavefrontaberration measuring device. A wavefront aberration measuring device isdescribed in Japanese patent application Publication No. JP2003-100613A, hereby incorporated by reference. The wavefront aberrationmeasuring device is configured to measure aberration of a wavefront, forexample using a Shack-Hartmann method. Such a wavefront aberrationmeasuring device may also be referred to as an aberration sensor. In anembodiment the sensor holder 206 is provided with a sensor such as anilluminance monitor. The illuminance monitor is configured to receivethe radiation beam B on an image plane of the projection system PS andto measure at least one property of the radiation beam B provided by theprojection system PS. In an embodiment the wavefront aberrationmeasuring device and/or the illuminance monitor are located on a topsurface of the sensor holder 206.

In an embodiment, one of the sensors held by the sensor holder 206 isarranged to measure an aberration of the projection system PS, a pupilof the projection system PS, and/or a polarisation of the illuminationsystem IL. Measurement data obtained by one of the sensors held by thesensor holder 206 may be used for conditioning or controlling a propertyof the projection system PS, the patterning device MA, the illuminationsystem IL, and/or the radiation source SO in order to improve theimaging quality of an exposure apparatus. When the sensor is arranged tomeasure the aberration of the projection system PS, a simulation modelcan be used to predict a distortion of an image on the substrate W,i.e., an aerial image of a pattern projected onto the substrate W.Additionally or alternatively, the simulation model can be used topredict a change in the aberration of the projection system PS and/orcan be used to predict a distribution of an illumination pupil of theillumination system IL. Additionally or alternatively, the simulationmodel can be used to predict a pattern created on the substrate W.Additionally or alternatively, a wavefront aberration measuring deviceand/or an aerial image measuring device may be used to calibrate, updateand/or improve the simulation model. The use of a simulation model isnot limited to when the sensor is arranged to measure the aberration ofthe projection system PS. In an alternative embodiment, a uniformitysensor is used (instead of the aberration sensor) to calibrate, updateor improve the simulation model. The uniformity sensor may be supportedby the sensor holder 206. Examples of a simulation model (or analgorithm used in a simulation model) that can be used in the context ofthe invention are disclosed in Japanese patent application publicationsNo. JP 2013-165134A and No. JP 2014-165291A and the PCT-applicationpublications No. WO 2011/102109A1, No. WO 2014/042044A1 and No. WO2015/182788A1, hereby incorporated by reference. The examples of thesensors mentioned are schematically illustrated in the figures as asquare, a circle and a triangle on the sensor holder 206. In anembodiment, the shape of the sensors may be different than illustrated.

In an embodiment, the aerial image measuring device, configured tomeasure an aerial image of a pattern projected by the projection systemPS, comprises a detector, a fiducial plate and/or an optical element.The fiducial plate comprises a fiducial mark and/or a pair of aerialimage measurement slit patterns. The aerial image measuring device maycomprise multiple fiducial plates. In an embodiment, all parts of theaerial image measuring device are provided on the sensor holder 206.Alternatively, only part of the aerial image measuring device, e.g. onlythe detector, may be provided on the sensor holder 206. Alternatively oradditionally, part of the aerial image measuring device, e.g. a fiducialplate, may be provided on the substrate holder 202. Alternatively, theaerial image measuring device may be provided on a dummy wafer asdisclosed in the Japanese patent application publication No. JP2007-189180A, hereby incorporated by reference. Such a dummy wafer maybe loaded on the substrate holder 202 in place of the substrate W.

The exposure apparatus 200 may comprise an exchange mechanism 208 forproviding the sensor holder 206 to the mover 204, for removing thesensor holder 206 from the mover 204, for supporting the sensor holder206 and/or for moving the sensor holder 206.

FIG. 4 depicts the exposure apparatus 200 in a first situation. Themover 204 is arranged to couple with the sensor holder 206 in the firstsituation so as to move the sensor holder 206. When the mover 204 andthe sensor holder 206 are coupled to each other, a movement of the mover204 may cause a movement of the sensor holder 206. The mover 204 maymove the sensor holder 206 relatively to the projection system PS, sodifferent parts of the sensor holder 206 may be beneath the projectionsystem PS. For example, the mover 204 may move the sensor holder 206relatively to the projection system PS so multiple sensors on the sensorholder 206 can be exposed with the exposure beam from the projectionsystem PS (in other words, a property of the exposure beam can bemeasured by each of these sensors on the sensor holder 206).

As depicted in FIG. 4, both the substrate holder 202 and the sensorholder 206 are supported by the mover 204. The substrate holder 202 andthe sensor holder 206 may be arranged to move in unison relatively tothe mover 204 in the first situation. In case immersion techniques areapplied in the exposure apparatus 200, during the move in unison (i.e.,the movement of the substrate holder 202 and the sensor holder 206 inunison), immersion liquid may be transferred from one of the substrateholder 202 and the sensor holder 206 to the other of the substrateholder 202 and the sensor holder 206. During the move in unison, thesubstrate holder 202 and the sensor holder 206 may be in contact witheach other or separated from each other by a gap. The gap may be smallenough to limit or prevent leakage of immersion liquid between thesubstrate holder 202 and the sensor holder 206 during the move inunison. In case immersion techniques are practiced, the lithographicapparatus may comprise a liquid handling system configured to supply andconfine the immersion liquid to a space defined between the projectionsystem PS and at least one of the substrate holder 202, the substrate W,and the sensor holder 206.

FIG. 5 depicts the exposure apparatus 200 in a second situation. Themover 204 is arranged to decouple from the sensor holder 206 in thesecond situation so as to move without the sensor holder 206. In thesecond situation, the mover 204 can move without the sensor holder 206.In the second situation, the mover 204 supports the substrate holder 202and does not support the sensor holder 206. The sensor holder 206 issupported and/or moved by the exchange mechanism 208. When the sensorholder 206 is located near or at the projection system PS by theexchange mechanism 208, the sensor on the sensor holder 206 may performa measurement. The exchange mechanism 208 may move the sensor holder 206relatively to the projection system PS, so different parts of the sensorholder 206 may be located beneath the projection system PS. When themover 204 moves in the second situation, the mover 204 does not move themass of the sensor holder 206. In the second situation, the mover 204may move the substrate holder 202 relative to the projection system PSso as to exposure the target portions C. The second situation may beduring exposure. As the mover 204 does not need to move the mass of thesensor holder 206 in the second situation, the mover 204 may movefaster. Alternatively, the mover 204 may make use of smaller actuatorsto achieve a desired acceleration. In case the mover 204 moves faster,more target portions C may be exposed per unit of time, reducing thecosts per target portion C. In case the mover 204 makes use of smalleractuators, the lithographic apparatus may be less expensive (i.e., at alower tool price). The lithographic apparatus may be less expensive,because less expensive actuators may be needed, a less expensive coolingsystem, less expensive amplifiers, etc.

FIG. 6 depicts the exposure apparatus 200 in a third situation. Themover 204 supports the sensor holder 206. The exchange mechanism 208supports the substrate holder 202. The exchange mechanism 208 may movethe substrate holder 202 to a substrate unload location. When thesubstrate holder 202 is at the substrate unload location, a substratehandler may remove the substrate W from the substrate holder 202. Inaddition, a new substrate W may be placed on (or loaded onto) thesubstrate holder 202 at the substrate unload location. A new substrate Wmay be loaded onto the substrate holder 202 at another location, e.g.,at a substrate load location. In the third situation, the sensor holder206 may be located near or at the exposure device, e.g., the projectionsystem PS. When the sensor holder 206 is located near or at the exposuredevice, the sensor on the sensor holder 206 may perform a measurement.The mover 204 may move the sensor holder 206 relatively to theprojection system PS, so different parts of the sensor holder 206 may belocated beneath the projection system PS.

The sensor holder 206 may be provided with an actuator to moverelatively to the mover 204. For example, the actuator may be arrangedto move the sensor holder 206 relatively to the mover 204 in thex-direction or the y-direction. The actuator system may comprise anarray of coils and an array of magnets. One of the array of coils andthe array of magnets may be provided on the sensor holder 206. The otherof the array of coils and the array of magnets may be provided on themover 204. The array of coils and the array of magnets may interact witheach other to provide a driving force to move the sensor holder 206relatively to the mover 204. Alternatively, the actuator may be providedwith a single magnet or with a single coil. Additionally, a sensorsystem may be provided to determine a position of the sensor holder 206relative to the mover 204. A controller may be provided that controlsthe actuator system based on a signal from the sensor system.

FIG. 7 depicts a further embodiment of the invention. The left part ofFIG. 7 depicts a side view of the mover 204 supporting the substrateholder 202. The substrate holder 202 supports the substrate W of acertain diameter. The diameter may, e.g., be one of 12.5 mm or 50 mm or100 mm or 150 mm or 200 mm or 300 mm or 450 mm. It may be beneficial ifthe exposure apparatus 200 is arranged to hold a further substrate W2having a different diameter than substrate W, as shown in the right partof FIG. 7. The right part of FIG. 7 shows the mover 204 supporting afurther substrate holder 702. The further substrate holder 702 isarranged to hold the further substrate W2. The diameter of the furthersubstrate W2 is larger than the diameter of substrate W. The diameter ofthe further substrate W2 may, e.g., be one of 12.5 mm or 50 mm or 100 mmor 150 mm or 200 mm or 300 mm or 450 mm. The further substrate holder702 is larger than the substrate holder 202. Alternatively, the furthersubstrate holder 702 may be smaller than the substrate holder 202. Toaccommodate the further substrate holder 702, the mover 204 may have twoparts; a left part 706 and a right part 704. Together, the left part 706and the right part 704 are arranged to support the substrate holder 202and the further substrate holder 702. When supporting the substrateholder 202, the left part 706 and the right part 704 are at a distance710 from each other. When supporting the further substrate holder 702,the left part 706 and the right part 704 are at a distance 720 from eachother. In case the further substrate holder 702 is larger than thesubstrate holder 202, the distance 720 is larger than the distance 710,so there is more space between the left part 706 and the right part 704to support the further substrate holder 702 (i.e., in this case, theleft part 706 and the right part 704 are more apart from each other).The left part 706 and the right part 704 may be manually adjustable toset the distances 710 and 720, or the mover 204 may be provided with anactuator to set (or adjust) the distances 710 and 720. The actuator maycomprise a lead screw or a piezo actuator or any other suitable actuatorto move the left part 706 and the right part 704 relative to each other.The mover 204 may comprise a sensor to provide a signal representativeof the distances 710 and 720. The signal may be used as a control signalfor the actuator to set (or adjust) the distances 710 and 720.

The embodiment of FIG. 7 may provide the benefit of having a singlelithographic apparatus that is able to process substrates with differentsizes. An IC-manufacturer does not have to buy a dedicated lithographicapparatus for each size of substrate; instead, a single lithographicapparatus processes substrates with different sizes, which results in anefficient use of the lithographic apparatus. The lithographic apparatusmay be provide with a substrate holder handler. The lithographicapparatus may be provide with multiple substrate holder handlers. Thesubstrate holder handler is arranged to couple with the substrate holder202 and to remove the substrate holder 202 from the lithographicapparatus. The substrate holder handler is arranged to add the substrateholder 202 to the lithographic apparatus, for example, by putting thesubstrate holder 202 onto the mover 204. Similarly, the substrate holderhandler may be arranged to add to and remove from the lithographicapparatus the other substrate holder 212 and/or the further substrateholder 702. For example, the exchange mechanism 208 may form thesubstrate holder handler. The exchange mechanism 208 may comprisemultiple substrate holder handlers, and each of the substrate holderhandler may be independently controlled. When the IC-manufacturer wantsto expose a different size or type of substrate W, the substrate holderhandler can remove the current substrate holder (i.e., the substrateholder currently in use) from the lithographic apparatus and replace itwith another type of substrate holder that is suitable for the differentsize or type of substrate W. In this embodiment, the other substrateholder 212 may have the same size as the substrate holder 202, whereasthe further substrate holder 702 may have a different size than thesubstrate holder 202. In this embodiment, there may be another substrateholder whose size is the same as the further substrate holder 702. Inthis embodiment, the substrate holder 202 and the other substrate holder212 may be replaced with the further substrate holder 702 and anothersubstrate holder whose size is the same as the further substrate holder702 when the IC-manufacturer wants to expose a different size ofsubstrate W. The substrate holder handler may be very similar to a waferhandler, and may, for example, comprise a robotic arm and/or a gripperto engage with the substrate holder.

The left part 706 and the right part 704 may each be provided with acoil array 740. The coil array 740 may extend in the y-direction. Thesubstrate holder 202 and the further substrate holder 702 may bearranged with a magnet array 730. The magnet array 730 may extend in they-direction. Alternatively, the left part 706 and the right part 704each are provided with the magnet array 730, and the substrate holder202 and the further substrate holder 702 are provided with the coilarray 740. The magnet array 730 and the coil array 740 together form anactuator system to move the substrate holder 202 and the furthersubstrate holder 702 relatively to the mover 204 in the y-direction. Theactuator system may be arranged to move the substrate holder 202 and thefurther substrate holder 702 relatively to the mover 204 over a distanceof one or several target portions C. This distance may be less than 100mm or less than 50 mm or less than 20 mm or less than 10 mm or less than5 mm or less than 2 mm. The actuator system may alternatively or inaddition be arranged to move the substrate holder 202 relative to themover 204 in the x-direction. A range of movement in the x-direction maybe substantial smaller than a range of movement in the y-direction. Forexample, the actuator system may move the substrate holder 202 relativeto the mover 204 in the x-direction over a range of less than 5 mm,e.g., less than 2 mm, e.g., less than 1 mm. The left part 706 and theright part 704 each may form a U-shape. The U-shape may form a spaceinto which a position measurement system may extend. For example, anencoder system extends through the U-shape. The mover 204 may bearranged such that the substrate holder 202 may be coupled and decoupledto the mover 204 by moving along the direction of the magnet array 730,i.e., in the y-direction of FIG. 7. One of the magnet array 730 and thecoil array 740 may form part of the actuator to move the sensor holder206 relatively to the mover 204.

The mover 204 may support a guide system. The guide system may bearranged to guide a movement of the left part 706 and the right part 704in the x-direction relatively to the each other. For example, the guidesystem comprises a guide rail to allow a movement of the left part 706along the x-direction relatively to the right part 704.

The guide rail that guides the left part 706 may be provided with twoend stops. One end stop may be at one side of the guide rail. When theleft part 706 is positioned at the one end stop, the left part 706 maybe set to support the substrate holder 202. The other end stop may be atthe other side of the guide rail. When the left part 706 is positionedat the other end stop, the left part 706 may be set (adjusted) tosupport the further substrate holder 702. Similarly, the guide rail thatguides the right part 704 may be provided with two end stops. When theright part 704 is positioned at the one end stop, the right part 704 maybe set to support the substrate holder 202. The other end stop may be atthe other side of the guide rail. When the right part 704 is positionedat the other end stop, the right part 704 may be set to support thefurther substrate holder 702.

In an embodiment, the substrate holder 202 is arranged to hold thesubstrate W and the further substrate W2. For example, the substrateholder 202 may be provided with a clamping device to clamp the substrateW and the further substrate W2. The clamping device may provide aclamping force, e.g., a vacuum force or an electrostatic force, on afirst area when clamping the substrate W. The clamping device mayprovide the clamping force on a second area when clamping the furthersubstrate W2. The second area may be larger than the first area. Thesecond area may have a larger diameter than the first area.

FIG. 8 depicts an embodiment according to the invention. In the leftpart of FIG. 8, the mover 204 supports the substrate holder 202 and thesensor holder 206. The sensor holder 206 has a width 800 and a length802. The length 802 substantially equals a size of the substrate holder202. For example, the size of the substrate holder 202 is about thediameter of the substrate W. The length 802 is about the diameter of thesubstrate W. The length 802 may substantially equal the size of thesubstrate holder 202 and may be long enough to accommodate a markerarray 810. The marker array 810 may provide (or comprise) alignmentmarkers along a distance about equal to the diameter of the substrate W;in other words, multiple alignment markers are arranged along the markerarray 810. Further, the sensor holder 206 holds sensors 850, 852 and854. At least one of sensors 850, 852 and 854 may comprise theilluminance irregularity sensor, the wavefront aberration measuringdevice or the uniformity sensor mentioned above. For example, the sensor850 may comprise the illuminance irregularity sensor, the sensor 852 maycomprise the wavefront aberration measuring device, and the sensor 854may comprise the uniformity sensor. At least one of sensors 850, 852 and854 may not be a sensor, but may be the cleaning device instead. Atleast one of sensors 850, 852 and 854 may be another type of sensor.

As shown in the right part of FIG. 8, the mover 204 supports the furthersubstrate holder 702, which is larger than the substrate holder 202 tosupport the further substrate W2. Because the further substrate W2 islarger than the substrate W, the marker array 810 may not be largeenough (or long enough) to provide sufficient alignment markers and/orto properly arrange alignment markers. In order to solve this issue, thesensor holder 206 is provided with a further marker array 820. Thefurther marker array 820 is larger than the marker array 810. To supportthe further marker array 820, the width 800 substantially equals a sizeof the further substrate holder 702, meaning that the width 800 islonger than the length 802 in case the further substrate holder 702 islarger than the substrate holder 202.

As shown in FIG. 8, the sensor holder 206 has a first orientation in theleft part of FIG. 8, and a second orientation in the right part of FIG.8. In the first orientation, the sensor holder 206 has a first anglealong an axis perpendicular to a horizontal plane. In the firstorientation, the width 800 is aligned along the y-axis and the length802 is aligned along the x-axis. The first orientation may be defined asan angle along the z-axis of 0°. In the second orientation, the sensorholder 206 has a second angle along the axis perpendicular to thehorizontal plane, wherein the first angle is different from the secondangle. In the second orientation, the length 802 is aligned along they-axis and the width 800 is aligned along the x-axis. The secondorientation may be defined as an angle along the z-axis of 90°. In anembodiment, the difference between the angle in the first orientationand the angle in the second orientation may be a value other than 90°,for example 30°, or 45°, or 120° or 180°. The shape of the sensor holder206 may be different from a rectangular shape, for example triangular orT-shaped.

In an embodiment, the sensor holder 206 has a length 802 and a width 800that is suitably large for both the substrate holder 202 and the furthersubstrate holder 702 in only the first orientation. Alternatively, twosensor holders 206 are provided, wherein one sensor holder is largerthan the other sensor holder.

In an embodiment, the sensor holder 206 is arranged to receive aradiation beam (or an exposure beam) from the substrate holder 202. Forexample, the projection system PS propagates the exposure beam to thesubstrate holder 202. Via the substrate holder 202 at least part of theexposure beam is directed to the sensor holder 206. In an embodiment,the substrate holder 202 comprises a marker 830. The projection systemPS exposes the marker 830 with the exposure beam to project an image onthe marker 830. The exposure beam comprises information about the imageprojected on the marker 830. As the exposure beam propagates through themarker 830 and to the sensor holder 206, information about the image ispropagated to the sensor holder 206. The sensor holder 206 may beprovided with a detector 840 to receive the exposure beam and to provide(or generate) a signal representing the information about the imageprojected on the marker 830. For example, the information may be aposition of the image on the marker 830, an interference pattern betweenthe image and the marker 830, a distortion of the image as projected onthe marker 830 or an intensity of the exposure beam. In addition to thedetector 840, the sensor holder 206 may be provided with at least oneadditional detector. One of the at least one additional detector may bearranged on a side of the sensor holder 206 that is different from theside of the sensor holder 206 on which the detector 840 is arranged. Forexample, the detector 840 is arranged on the side of length 802 and theadditional detector is arranged on the side of width 800. The additionaldetector may face the substrate holder 202 or the further substrateholder 702 when the sensor holder 206 is in the second orientation.

In an embodiment, the marker 830 and the detector 840 may be componentsof an aerial image measuring device configured to measure an aerialimage of a pattern projected by the projection system PS. In thiscontext, the marker 830 may comprise a fiducial plate or may comprisemultiple fiducial plates. The detector 840 may provide information (orgenerate a signal representing information) about an aerial image (inother words, an aerial image measuring device measures an aerial image)when the substrate holder 202 and the sensor holder 206 are bothsupported by the mover 204. The detector 840 may provide information (orgenerate a signal representing information) about an aerial image whenthe substrate holder 202 and the sensor holder 206 perform the move inunison.

In an embodiment, the detector is not arranged on the sensor holder 206,but somewhere else, such that the sensor holder 206 is moveable relativeto the detector. For example, the detector 840 may be arranged on themover 204 or the detector 840 may be arranged on a stationary frame. Inthis embodiment, the sensor holder 206 may be provided with an opticalcomponent to direct the exposure beam to the detector 840.

As further depicted in FIG. 2 and FIG. 9, the exposure apparatus 200 maycomprise an exposure device, e.g., projection system PS, and ameasurement device 220. The exposure device is arranged to exposure thesubstrate W with the exposure beam. The measurement device 220 isarranged to provide measurement information of the substrate W (i.e.,arranged to measure the substrate W). The exposure device and themeasurement device 220 are distant to each other. The mover 204 isarranged to support the substrate holder 202 while near the exposuredevice.

The measurement device 220 may be any suitable device arranged toprovide measurement information of the substrate W (i.e., arranged tomeasure the substrate W). For example, the measurement device 220 mayprovide of information about a height profile of the substrate W, e.g.,about the flatness of the substrate W. Information about the heightprofile may be used to position the substrate W to a certain z-positionduring exposure of a certain target portion C, to create an in-focusimage on the target portion C. Additionally or alternatively, themeasurement device 220 may be arranged to provide information aboutin-plane deformation of the substrate W. For example, the measurementdevice 220 may provide information about the positions of substratealignment marks P1, P2 on the substrate W. The information about thepositions of substrate alignment marks P1, P2 may be used to determinethe positions of the substrate alignment marks P1, P2 relative to eachother or to compare the information with reference information. Theinformation about in-plane deformation may be used to position thesubstrate W to a certain x- and y-position during exposure of a certaintarget portion C, to create an image at a correct x- and y-position onthe substrate W.

The measurement device 220 may comprise multiple alignment sensors asdisclosed in the US patent application US 2009-0233234A1, herebyincorporated by reference. In other words, the measurement device 220may comprise an alignment system that comprises such multiple alignmentsensors. Alternatively, the alignment system may comprise a singlealignment sensor. The substrate W may be moved relative to the singlealignment sensor during an alignment operation so the substratealignment marks P1, P2 face the single alignment sensor subsequently.During the alignment operation, the alignment sensor may generateposition information, which is a type of measurement information, basedon the positions of the substrate alignment marks P1, P2; in otherwords, the alignment sensor may measure the positions of the substratealignment marks P1, P2. Additionally or alternatively, during thealignment operation, the alignment sensor may generate positioninformation based on the positions of overlay marks, which may belocated in a target portion C. Additionally or alternatively, during thealignment operation, the alignment sensor may generate positioninformation based on the positions of both the substrate alignment marksP1, P2 and overlay marks; in other words, the alignment sensor maymeasure the positions of both the substrate alignment marks P1, P2 andoverlay marks.

The exposure device and the measurement device 220 are distant to eachother, so when the substrate W is at the exposure device, the substrateW is not at the measurement device 220 and vice versa. The substrate Wmay be moved from a location, where the measurement device 220 performsmeasurements to provide the measurement information, to anotherlocation, wherein the exposure device exposes the substrate W. In anembodiment, the exposure device and the measurement device 220 may beadjacent to each other. For example, when one edge of the substrate W isat the measurement device 220, another edge of the substrate W is at theexposure device.

In an embodiment, see FIG. 2, the mover 204 is arranged to support thesubstrate holder 202 while the substrate holder 202 is near the exposuredevice. A stationary support 210 is provided to support anothersubstrate holder 212 while the other substrate holder 212 is near themeasurement device 220. The other substrate holder 212 may be the sameor similar to one of the substrate holder 202 and the further substrateholder 702. The stationary support 210 may be provided with an actuatorsystem to move the other substrate holder 212 relative to the stationarysupport 210. The actuator system may be part of a movement device 230arranged to move the other substrate holder 212 while supported by thestationary support 210. For example, the movement device 230 comprises arobot arm arranged to move the other substrate holder 212 in the x- andy-direction. The movement device 230 may comprise multiple robotic arms.The robot arm may be arranged to rotate the other substrate holder 212along the z-axis. In other words, during operation of the measurementdevice 220 (e.g., during the alignment operation), the movement device230 may move the other substrate holder 212 with respect to thestationary support 210 in the horizontal directions. In an embodiment,the other substrate holder 212 is provided with one of the magnet array730 and the coil array 740. The actuator system may be partly formed bythe one of the magnet array 730 and the coil array 740. Another part ofthe actuator system may be arranged on a top surface of the stationarysupport 210. For example, the top surface is provided with an array ofmagnets or an array of coils. The array of magnets or the array of coilsmay be arranged in a 2D-array extending in both the x-direction and they-direction. In brief, during operation of the measurement device 220,the other substrate holder 212 may be moved with respect to thestationary support 210 (e.g., in the horizontal directions) by theactuator system (or part of the actuator system) provided on the othersubstrate holder 212 itself.

In an embodiment, the exchange mechanism 208 may be arranged to transferthe other substrate holder 212 from the stationary support 210 to themover 204. Additionally or alternatively, the exchange mechanism 208 maybe arranged to transfer the substrate holder 202 from the mover 204 tothe stationary support 210. The exchange mechanism 208 may move theother substrate holder 212 while the other substrate holder 212 issupported by the stationary support 210 during operation of themeasurement device 220. The movement device 230 and the exchangemechanism 208 may be arranged and operated similarly. The movementdevice 230 and the exchange mechanism 208 may be simultaneously operatedat different locations in the exposure apparatus 200. For example, asdepicted in FIGS. 2 and 3, the movement device 230 may hold (and/ormove) the other substrate holder 212 while the exchange mechanism 208may hold (and/or move) the sensor holder 206.

The top surface of the stationary support 210 may be provided with gasoutlets to provide a gas film between the top surface and the othersubstrate holder 212. The gas film may function as a gas bearing,supporting the other substrate holder 212 without physical contactbetween the other substrate holder 212 and the top surface. Each of thegas outlets may be provided with a valve. The valve may be arranged toopen when the other substrate holder 212 is near or above the gas outletand may be arranged to close when the other substrate holder 212 is awayfrom the gas outlet. The gas provided by the gas outlet may compriseair, nitrogen or any other suitable gas.

In an embodiment as shown in FIG. 9, the exposure apparatus 200 may beprovided with a first encoder head 910 and a first scale 915. Thestationary support 210 comprises a recess for holding the first encoderhead 910. The first scale 915 is arranged at a bottom surface of theother substrate holder 212. The first encoder head 910 faces the firstscale 915 while the other substrate holder 212 is near or at themeasurement device 220 and is arranged to provide (or generate) a firstsignal representative of positional information of the other substrateholder 212. For example, the first encoder head 910 may provide (orgenerate) a signal representing the position of the other substrateholder 212 along the x-axis, and/or along the y-axis and/or along thez-axis and/or a rotation about the x-axis, and/or a rotation about they-axis, and/or a rotation about the z-axis. The first encoder head 910may be an encoder head system comprising multiple encoder heads and/orcomprising other position sensors than encoder heads, for examplecapacitive or interferometric sensors. Such an encoder head system mayalso be referred to as a position measurement device or a positionmeasurement system.

The first encoder head 910 may be coupled to the stationary support 210via a dynamical isolator. The dynamical isolator may comprise amechanical spring or a damper. The mechanical spring may be a helicalspring or a leaf spring. The damper may comprise a viscous damper or aviscoelastic damper. The dynamical isolator may comprise an actuator, asensor and a controller. The sensor may be arranged to detect avibration of the stationary support 210. Based on input from the sensor,the controller may control the actuator to actuate so as to prevent thevibration of the stationary support 210 to vibrate the first encoderhead 910. For example, the actuator is a piezo-actuator or a reluctanceactuator or a Lorentz actuator. Alternatively, the sensor, controllerand actuator may be arranged to have the first encoder head 910 maintaina desired position relative to a reference, independently of vibrationsof the stationary support 210. The reference may be the measurementdevice 220 or the exposure device.

As shown in FIG. 9, the exposure device, e.g., projection system PS, issupported by a frame 940. In an embodiment, the exposure device ismovable relative to the frame 940. When the exposure device is able tomove relative to the frame 940, the exposure device is able to changethe path of the exposure beam. For example, when the exposure device isable to move in the x-direction, the exposure device is able to shiftthe path of the exposure beam in the x-direction. By shifting the pathof the exposure beam, a larger portion of the substrate W can be exposedby the exposure beam without movement of the substrate holder 202.Alternatively or in addition, by shifting the path of the exposure beamin the direction of movement of the substrate holder 202, a certain partof the substrate W can be exposed for a longer period of time. Theexposure device may be moveable relative to the frame 940 along thex-axis, the y-axis or both. The exposure device may be moved by anactuator such as a piezo actuator or a Lorentz actuator. The exposuredevice may be guided by a guiding device. The guiding device maycomprise flexible elements such as leaf springs. The guiding device maycomprise a gas bearing. Alternatively or in addition, the projectionsystem PS may be supported by the frame 940 via an AVIS (ActiveVibration Isolation System). Such an AVIS may comprise a damper, aspring, a position sensor, and/or an actuator (such as a voice coilmotor). In an embodiment, the exposure device is movable with respect tothe frame 940 in the vertical direction, i.e., along the z-axis. TheAVIS enables to attenuate vibrations that can be propagated between theframe 940 and the projection system PS. An example of an AVIS, which canbe used in the context of the invention, is disclosed in Japanese patentapplication publication No. JP 2016-194599A, hereby incorporated byreference. As vibrations are a typical type of undesired disturbancethat deteriorates the imaging quality of a lithographic apparatus, anAVIS can improve the imaging quality of a lithographic apparatus withoutdeteriorating the overall productivity.

In an embodiment, the exposure apparatus 200 is provided with a furthermeasurement device 950 arranged to provide further measurementinformation of the substrate W (i.e., arranged to perform a furthermeasurement of the substrate W). The further measurement device 950 iscloser to the exposure device (e.g., the projection system PS) than themeasurement device 220. The measurement device 220 is further away fromthe exposure device (e.g., the projection system PS) than the furthermeasurement device 950. The further measurement device 950 may besimilar to the measurement device 220 and may provide similarinformation about the substrate W. For example, the further measurementdevice 950 may be the same type of a sensor system as the measurementdevice 220, but the measurement device 220 may provide with informationabout the substrate W at a better accuracy than the further measurementdevice 950 by taking a longer measurement time; in other words, thefurther measurement device 950 may take less measurement time tocomplete a measurement of the substrate W. The further measurementdevice 950 may perform a measurement of the substrate W while thesubstrate holder 202 is supported by the mover 204.

Information provided by the further measurement device 950 may be usedto determine the z-position of the surface of the substrate W relativeto an image plane of the exposure device. The further measurement device950 may comprise a levelling sensor system that provides informationabout a height profile of the substrate W, e.g, a flatness of thesubstrate W. A levelling sensor system may also be referred to as anauto-focus system. The control unit may make use of both the informationabout the height profile of the substrate W as well as informationprovided by the aerial image measuring system to determine a positionalrelationship between the substrate W and the patterning device MA. Thecontrol unit may process multiple signals obtained by the levellingsensor system and the aerial image measuring system to determine thepositional relationship between the substrate W and the patterningdevice MA. The control unit may process multiple signals and/or executean algorithm as disclosed in the PCT-application publication No. WO2005/096354A1, hereby incorporated by reference.

The levelling sensor system may comprise a light source to provide abeam of radiation. The beam of radiation (e.g., light) may be directedto the top surface of the substrate W. The beam of radiation isreflected by the top surface back to the levelling sensor system. Basedon the reflection (i.e., based on the reflected light), the levellingsensor system may generate a signal representative of the heightprofile. The light source may provide the beam of radiation with aplurality of wavelengths and/or with a continuous spectrum. Theradiation beam may comprise infrared light, visible light and/orUV-light. The light source may comprise an LED (light-emitting diode) ormay comprise multiple LED's. The light source may have LED's withdifferent colours such as orange, red, green, cyan, blue and violet(e.g., having a peak wavelength of or about 630, 605, 560, 505, 470 or405 nm, respectively). The leveling sensor system may provide the beamof radiation at a slanted angle with the substrate W. The levelingsensor system may provide the beam of radiation such that the beam ofradiation is incident on a large part of the substrate W, for example,along a line across the substrate W.

Information of the further measurement device 950 may be used todetermine the x- and y-positions the substrate W relative to an image ofa reference mark of the patterning device MA, for example the maskalignment marks M1, M2. Additionally or alternatively, the furthermeasurement device 950 may provide information about the positions ofsubstrate alignment marks P1, P2 on the substrate W; in other words, thefurther measurement device 950 may measure the positions of substratealignment marks P1, P2 on the substrate W. The information about thepositions of substrate alignment marks P1, P2 may be used to determinethe positions of the substrate alignment marks P1, P2 relative to eachother or to compare the information with reference information. Thefurther measurement device 950 may comprise a wafer alignment sensorsystem that provides information about in-plane deformation of thesubstrate W. The further measurement device 950 may comprise multiplealignment sensors as disclosed in the US patent application US2009-0233234A1, hereby incorporated by reference. In other words, thewafer alignment sensor system may comprise such multiple alignmentsensors. Alternatively, the wafer alignment sensor system may comprise asingle alignment sensor. The information about in-plane deformation maybe used to position the substrate W to a certain x- and y-positionduring exposure of a certain target portion C, to create an image at acorrect x- and y-position on the substrate W. The control unit may makeuse of both the information about the in-plane deformation of thesubstrate W and information provided by the aerial image measuringsystem to determine a positional relationship between the substrate Wand the patterning device MA. The control unit may process multiplesignals obtained by the wafer alignment sensor system and the aerialimage measuring system to determine the positional relationship betweenthe substrate W and the patterning device MA. The control unit mayprocess multiple signals and/or execute an algorithm as disclosed in thePCT-application publication No. WO 2007/097379A1, hereby incorporated byreference.

In an embodiment, the exposure apparatus 200 comprises a second encoderhead 920 and a second scale 925. The second scale 925 is arranged at abottom surface of the substrate holder 202. The second encoder head 920is arranged to face the second scale 925 so as to provide (or generate)a second signal representative of positional information of thesubstrate holder 202. The second encoder head 920 faces the second scale925 while the substrate holder 202 is near or at the exposure device,e.g., the projection system PS, and is arranged to provide (or generate)a second signal representative of positional information of thesubstrate holder 202. For example, the second encoder head 920 mayprovide (or generate) the second signal representing the position of thesubstrate holder 202 along the x-axis, and/or along the y-axis and/oralong the z-axis and/or a rotation about the x-axis, and/or a rotationabout the y-axis, and/or a rotation about the z-axis. The second encoderhead 920 may be an encoder head system comprising multiple encoder headsand/or comprising other position sensors than encoder heads, for examplecapacitive or interferometric sensors. Such an encoder head system mayalso be referred to as a position measurement device or a positionmeasurement system. The second encoder head 920 may be mounted on ameasurement arm. The measurement arm may be attached to the frame 940and may extend below the substrate holder 202. The second encoder head920 may be located along the optical axis of the exposure device.

The substrate holder 202 and the other substrate holder 702 may exchangeposition such that the first encoder head 910 faces the second scale 925and such that the second encoder head 920 faces the first scale 915. Inthat situation, the first encoder head 910 may provide (or generate) thefirst signal that is representative of positional information of thesubstrate holder 202. In that situation, the second encoder head 920 mayprovide (or generate) the second signal that is representative ofpositional information of the other substrate holder 702.

In an embodiment, the exposure apparatus 200 comprises a third encoderhead 930 and a third scale 935. The third scale 935 is arranged at abottom surface of the sensor holder 206. The third encoder head 930 isarranged to face the third scale 935 so as to provide (or generate) athird signal representative of positional information of the sensorholder 206. The third encoder head 930 faces the third scale 935 whilethe sensor holder 206 is supported by the exchange mechanism 208, and isarranged to provide the third signal representative of positionalinformation of the sensor holder 206. For example, the third encoderhead 930 may provide the third signal representing the position of thesensor holder 206 along the x-axis, and/or along the y-axis and/or alongthe z-axis and/or a rotation about the x-axis, and/or a rotation aboutthe y-axis, and/or a rotation about the z-axis. The third encoder head930 may be an encoder head system comprising multiple encoder headsand/or comprising other position sensors than encoder heads, for examplecapacitive or interferometric sensors. Such an encoder head system mayalso be referred to as a position measurement device or a positionmeasurement system. The third encoder head 930 may be mounted on afurther measurement arm. The further measurement arm may be attached tothe frame 940 and may extend below the sensor holder 206.

In an embodiment, the further substrate holder 702 may have the samesize as the substrate holder 202 or may have a different size. Forexample, in the embodiment of FIGS. 3 and 9, in a lithographic apparatusthat is compatible only with a single size of substrates, the othersubstrate holder 212 and/or the further substrate holder 702 may beidentical to the substrate holder 202. Alternatively or additionally, ina lithographic apparatus that is compatible only with a single size ofsubstrates made of different materials, the further substrate holder 702may have the same size as the substrate holder 202, but the furthersubstrate holder 702 may be made of a different material from thesubstrate holder 202. Alternatively, in the embodiment of FIGS. 7 and 8,in a lithographic apparatus that is compatible with multiple sizes ofsubstrates, the further substrate holder 702 may have a different sizethan the substrate holder 202, and the further substrate holder 702 maybe replaceable with the other substrate holder 212, whose size is thesame as the substrate holder 202. Additionally or alternatively, thefurther substrate holder 702 may hold a different type of substrate Wthan a substrate on the substrate holder 202; e.g., a dummy wafer may beloaded on the substrate holder 202 when the substrate W is loaded on thefurther substrate holder 702 at a certain moment during operation of alithographic apparatus. In an embodiment, the exposure apparatus 200comprises two substrate holders 202 and two further substrate holders702. The two substrate holders 202 may have the same size. The twofurther substrate holders 702 may have the same size or may be largerthan the two substrate holders 202. In a first operation mode, theexposure apparatus uses the two substrate holders 202 to hold substratesW, while storing the two further substrate holders 702, for example at astoring location in the exposure apparatus 200. The two furthersubstrate holders 702 may remain idle (i.e., remain unused) during thefirst operation mode. In a second operation mode, the exposure apparatususes the two further substrate holders 702 to hold substrates W, whilestoring the two substrate holders 202, for example at the storinglocation in the exposure apparatus 200. The two substrate holders 202may remain idle (i.e., remain unused) during the second operation mode.

The sensor holder 206 may take the position of the substrate holder 202such that the second encoder head 920 faces the third scale 935. In thatsituation, the second encoder head 920 may provide (or generate) thesecond signal that is representative of positional information of thesensor holder 206.

In an embodiment, there is provided an exposure apparatus comprising thesubstrate holder 202, the sensor holder 206, the mover 204 and theprojection system PS. The substrate holder 202 is for holding thesubstrate W. The sensor holder 206 is for holding a sensor. The mover204 is arranged for moving the substrate holder 202. The projectionsystem PS is arranged to provide a beam of radiation onto the substrateW. During exposure, the projection system PS provides the beam ofradiation onto the substrate W when the sensor holder 206 is decoupledfrom the mover 204. The mover 204 may couple with the sensor holder 206when the sensor measures a property of the projection system PS or theradiation beam.

The exposure apparatus may comprise the exchange mechanism 208 forproviding the sensor holder 206 to the mover 204 and for removing thesensor holder 206 from the mover 204.

The mover 204 may be arranged to move a further substrate holder 702 forholding a further substrate W2. The size of the further substrate W2 maybe different from the size of the substrate W. By configuring theexposure apparatus in such a way, the exposure apparatus can flexiblyand efficiently be compatible with different sizes of substrates. Asingle exposure apparatus that is able to expose substrates withdifferent sizes can improve the CoO (Cost of Ownership) and/or the TCO(Total Cost of Ownership), comparing to the case that each of multipleexposure apparatuses is dedicated to exposing a specific size ofsubstrates.

The sensor holder 206 has a length and a width. The length maysubstantially equal a size of the substrate holder 202. The widthsubstantially may equal a size of the further substrate holder 702. Thelength and the width may be different from each other.

The mover 204 may be arranged to support the sensor holder 206 in afirst orientation and in a second orientation. In the first orientation,the sensor holder 206 has a first angle along an axis perpendicular to ahorizontal plane. In the second orientation, the sensor holder 206 has asecond angle along the axis perpendicular to the horizontal plane. Thefirst angle is different from the second angle.

The mover may be arranged to decouple from the substrate holder so as tomove without moving the substrate holder.

The sensor holder 206 may be arranged to receive the radiation beam fromthe substrate holder 202. The substrate holder 202 may comprise a marker(e.g., the marker 830). The radiation beam may comprise informationabout an image projected on the marker. The sensor holder 206 may bearranged to propagate the radiation beam to a detector (e.g., thedetector 840). The sensor holder 206 may be movable relative to thedetector.

The exposure apparatus may comprise an exposure device and a measurementdevice. The exposure device is arranged to expose the substrate with anexposure beam. The measurement device is arranged to provide measurementinformation of the substrate W. The exposure device and the measurementdevice are distant to each other. The mover 204 is arranged to supportthe substrate holder 202 while near the exposure device.

The exposure apparatus may comprise the stationary support 210 arrangedto support the substrate holder 202 while near the measurement device.

The exposure apparatus may comprise a first encoder head 910 and a firstscale 915. The stationary support 210 may comprise a recess for holdingthe first encoder head 910. The first scale is arranged at a bottomsurface of the substrate holder 202. The first encoder head 910 facesthe first scale 915 while the substrate holder 202 is near themeasurement device 220 and is arranged to provide a signalrepresentative of positional information of the substrate holder 202.The first encoder head 910 may be coupled to the stationary support 210via a dynamical isolator. The exposure apparatus may comprise a movementdevice arranged to move the substrate holder while supported by thestationary support. The exposure apparatus may comprise the frame 940for supporting the exposure device. The exposure device may be movablerelative to the frame. The exposure apparatus may comprise a furthermeasurement device 950 arranged to provide further measurementinformation of the substrate W. The further measurement device 950 maybe closer to the exposure device than the measurement device.

The exposure apparatus may comprise a second encoder head 920. Thesecond encoder head 920 is arranged to face the first scale 915 so as toprovide a second signal representative of positional information of thesubstrate holder 202.

The exposure apparatus may comprise a third encoder head 930 and a thirdscale 935. The third scale 935 is arranged at a bottom side of thesensor holder 206. The third encoder head 930 is arranged to face thethird scale 935, so as to provide a third signal representative ofpositional information of the sensor holder 206.

The embodiment of the lithographic apparatus of FIG. 9 may be operatedin the following way. The following way is illustrated in FIGS. 10A-10Iin a schematic top-view.

A first substrate in a first lot W1L1 is loaded on the further substrateholder 702; see FIG. 10A. The first substrate in the first lot W1L1 isalso referred to as the first substrate W1L1 in this embodiment. Thefurther substrate holder 702 moves the first substrate W1L1 to themeasurement device 220. The measurement device 220 provides measurementinformation of the first substrate W1L1. The measurement information iswafer alignment information, which is information relating to the shapeand the position of the first substrate W1L1. The measurement device 220provides fine wafer alignment information, which is based on a largenumber of measurements, e.g. based on measuring the positions of a largenumber of the substrate alignment marks relative to one another or tocompare the information with reference information. In this embodiment,all substrate alignment marks on a wafer, e.g., 96 substrate alignmentmarks on a wafer may be measured by the measurement device 220.Substrate alignment marks on a wafer may also be referred to as waferalignment marks. Additionally, the measurement device 220 may alsomeasure overlay marks on the first substrate W1L1. The fine waferalignment information provides accurate information about a large partof the surface (or the entire surface) of the first substrate W1L1. Atthis moment, the sensor holder 206 may be located beneath the projectionsystem PS, and the sensor on the sensor holder 206 may measure theproperty of the projection system PS, the property of the aerial image,and/or the property of the exposure beam.

As depicted in FIG. 10B, after the measurement device 220 has collectedthe measurement information, the movement device 230 transports thefirst substrate W1L1 from the further substrate holder 702 to thesubstrate holder 202. The movement device 230 is arranged to pick up thefirst substrate W1L1 from the further substrate holder 702 and to placethe first substrate W1L1 onto the substrate holder 202. In other words,the movement device 230 is configured to unload the first substrate W1L1from the further substrate holder 702 and then to load the firstsubstrate W1L1 on the substrate holder 202. At this moment, the movementdevice 230 may load a second substrate in the first lot W2L1 on thefurther substrate holder 702. The second substrate in the first lot W2L1is also referred to as the second substrate W2L1. In an embodiment, themovement device 230 may comprise multiple robotic arms and/or multipleBernoulli chucks to enable to simultaneously handle the first substrateW1L1 and the second substrate W2L1. In other words, the movement device230 is not only configured to unload a substrate from the furthersubstrate holder 702 but also configured to load a substrate on thefurther substrate holder 702 in this embodiment.

As depicted in FIG. 10C, the substrate holder 202 locates the firstsubstrate W1L1 at (or beneath) the further measurement device 950. Thefurther measurement device 950 provides further measurement informationof the first substrate W1L1. The further measurement information isfurther wafer alignment information, which is information relating tothe shape and the position of the first substrate W1L1. The furthermeasurement device 950 provides coarse wafer alignment information,which is based on a small number of measurements, e.g. based onmeasuring the positions of a small number of the substrate alignmentmarks relative to one another or to compare the information withreference information. In this embodiment, a small number of thesubstrate alignment marks may, e.g., be between 3 and 16 substratealignment marks. In general, less measurement time is necessary formeasuring a smaller number of the substrate alignment marks; in otherwords, a shorter time in operating the further measurement device 950 isnecessary to obtain the coarse wafer alignment information, comparing tothe time necessary to obtain fine wafer alignment information by themeasurement device 220. When the measurement device 950 is collectingthe further measurement information, the sensor holder 206 is locatedbeneath the projection system PS. The sensor holder 206 may, e.g., besupported and/or moved by the exchange mechanism 208 as depicted in FIG.5. When the further measurement device 950 is collecting the furthermeasurement information, the sensor on the sensor holder 206 ismeasuring the property of the projection system PS, the property of theaerial image, and/or the property of the exposure beam. When the furthermeasurement device 950 is collecting the further measurementinformation, the measurement device 220 is collecting measurementinformation from the second substrate W2L1, which has been loaded on thefurther substrate holder 702 and is held by the further substrate holder702.

After the further measurement device 950 has collected the furthermeasurement information, i.e., as soon as coarse wafer alignmentinformation is obtained by the further measurement device 950, the mover204 moves the substrate holder 202 with the first substrate W1L1 beneaththe projection system PS; see FIG. 10D. The sensor holder 206 is movedaway from beneath the projection system PS. The sensor holder 206 may besupported and/or moved by the exchange mechanism 208 as depicted in FIG.9. When the first substrate W1L1 is beneath the projection system PS,the first substrate W1L1 is exposed with the exposure beam to projectthe pattern on the first substrate W1L1. Since a relatively short timeis necessary in operating the further measurement device 950, which islocated closer to the projection system than the measurement device 220,this configuration is beneficial in improving the throughput performanceof the lithographic apparatus. If the further measurement device 950 islocated far away from the projection system PS, and/or if another objectinterferes with the smooth movements of the substrate holder 202 and thesensor holder 206, the throughput performance of the lithographicapparatus will be deteriorated.

As depicted in FIG. 10E and in FIG. 9, during exposure of the firstsubstrate W1L1 on the substrate holder 202 (i.e., during stepping and/orscanning motions of the substrate holder 202 beneath the projectionsystem PS), the measurement device 220 continues measuring (collectingmeasurement information from) the second substrate W2L1 on the furthersubstrate holder 702. During exposure of the first substrate W1L1 on thesubstrate holder 202, the sensor holder 206 is located (or parked) at aplace inside the exposure apparatus 200, where the sensor holder 206does not interfere with the stepping and/or scanning motions of thesubstrate holder 202 and the measurement of the second substrate W2L1 onthe further substrate holder 702.

When all target portions C on the first substrate W1L1 have beenexposed, the substrate holder 202 is decoupled from the mover 204, andthe sensor holder 206 is coupled to the mover 204; in other words, thesubstrate holder 202 and the sensor holder 206 move in unison relativelyto the mover 204 as depicted in FIG. 10F and FIG. 4. The exchangemechanism 208 moves the substrate holder 202 with the first substrateW1L1 to a substrate unload location as recognized in FIG. 10G. When theexchange mechanism 208 moves the substrate holder 202 away from beneaththe projection system PS as depicted in FIG. 6, the mover 204 moves thesensor holder 206 beneath the projection system PS, which allows thesensor on the sensor holder 206 to start measuring the property of theprojection system PS or the property of the exposure beam as depicted inFIG. 10H. Meanwhile, the measurement device 220 continues collectingmeasurement information from the second substrate W2L1 on the furthersubstrate holder 702.

At the substrate unload location also as depicted in FIG. 10H, the firstsubstrate W1L1 is unloaded from the substrate holder 202, for example,by the movement device 230; the movement device 230 may be operatedsimilarly to how the movement device 230 has unloaded the firstsubstrate W1L1 from the further substrate holder 702 as described inFIG. 10B. After the first substrate W1L1 is unloaded from the substrateholder 202, the first substrate W1L1 leaves (or is transported to theoutside of) the lithographic apparatus; e.g., the first substrate W1L1is contained in a FOUP.

After the first substrate W1L1 is unloaded from the substrate holder202, the substrate holder 202 is coupled to the mover 204 as depicted inFIG. 10I; in other words, the substrate holder 202 and the sensor holder206 move in unison relatively to the mover 204 as depicted in FIG. 4.When the substrate holder 202 is coupled to the mover 204, the sensorholder 206 may be supported and/or moved by the exchange mechanism 208as depicted in FIG. 5. Alternatively, the sensor holder 206 may remainsupported by the mover 204 as depicted in FIG. 4. When the sensor holder206 is located beneath the projection system PS, e.g., by the exchangemechanism 208, by the mover 204, and/or by the actuator equipped on thesensor holder 206 itself, the sensor on the sensor holder 206 maymeasure the property of the projection system PS, the property of theaerial image, and/or the property of the exposure beam. The movementdevice 230 transports the second substrate W2L1 from the furthersubstrate holder 702 to the substrate holder 202 similarly to how themovement device 230 has transported the first substrate W1L1 from thefurther substrate holder 702 to the substrate holder 202 as described inFIG. 10B. The steps described above relating to the first substrate W1L1are now repeated for the second substrate W2L1. When the steps describedabove are completed for all substrates in the first lot, the same orsimilar operations may be repeated for substrates in a second lot.

FIG. 10A depicts that the exposure apparatus is arranged to hold thefirst substrate W1L1 on the further substrate holder 702 while themeasurement device 220 is acquiring the measurement information from thefirst substrate W1L1. At this moment, the sensor holder 206 may belocated beneath the projection system PS, and the sensor on the sensorholder 206 may perform a measurement. FIG. 10C depicts that the exposureapparatus is arranged to hold the first substrate W1L1 on the substrateholder 202 while the further measurement device 950 is acquiring thefurther measurement information from the substrate W1L1. At this moment,the measurement device 220 can already start measuring (acquiring themeasurement information from) the second substrate W2L1 on the furthersubstrate holder 702. FIG. 9 and FIG. 10E depict that the measurementdevice 220 continues measuring the second substrate W2L1 on the furthersubstrate holder 702 while the first substrate W1L1 on the substrateholder 202 is exposed. FIG. 10G depicts that the measurement device 220continues measuring the second substrate W2L1 on the further substrateholder 702 while the substrate holder 202 is moving away from theprojection system PS towards a substrate unload location. FIG. 10Hdepicts that the measurement device 220 continues measuring the secondsubstrate W2L1 on the further substrate holder 702 while the firstsubstrate W1L1 is unloaded from the substrate holder 202. At thismoment, the sensor holder 206 may be located beneath the projectionsystem PS, and the sensor on the sensor holder 206 may perform ameasurement.

By configuring and operating the lithographic apparatus in such a way,the measurement device 220 has a maximum amount of time to collect themeasurement information without limiting the throughput performance ofthe lithographic apparatus since it is not limited by the measurement merequired by the measurement device 220. Therefore, better imagingquality can be achieved without deteriorating the overall productivity.In other words, better overall productivity can be achieved whilesimultaneously qualifying for a certain sufficient imaging quality. Incontrast, if a longer measurement time is spent by the furthermeasurement device 950 (e.g., if fine wafer alignment information isobtained by the further measurement device 950), the lithographicapparatus will suffer from a trade-off between the throughputperformance and the imaging quality. Such a trade-off is also generallyobserved in a lithographic apparatus that comprises a single wafer stageand a single wafer alignment system. Additionally, the sensor on thesensor holder 206 can measure the property of the projection system PS,the property of the aerial image, and/or the property of the exposurebeam without interfering with exposure of a substrate; hence, betterimaging quality (and/or better uptime performance, e.g., in case thesensor holder 206 comprises a cleaning device) can be achieved withoutdeteriorating the throughput performance. Additionally, the measurementdevice 220 and the further measurement device 950 do not increase afootprint of the lithographic apparatus, which is also called theexposure apparatus, since the measurement device 220 and the furthermeasurement device 950 are smaller (especially in the horizontaldirections, i.e., on the xy-plane) than the substrate holder 202, thefurther substrate holder 702, or the substrate W. Consequently, theconfiguration of the exposure apparatus 200 is a solution to thetrilemma between the overall productivity, the imaging quality and theeconomy of an exposure apparatus.

The control unit may drive (or control a position of) the substrateholder 202 based on the measurement information and/or the furthermeasurement information. For example, based on the measurementinformation and/or the further measurement information, the control unitmay determine that a target portion C is not at a nominal position onthe substrate W (i.e., the position of a target portion C on thesubstrate W when the substrate W is undeformed). Additionally oralternatively, based on the measurement information and/or the furthermeasurement information, the control unit may derive the position on the(deformed) substrate W onto which an aerial image of the pattern shouldbe projected. The control unit may drive the substrate holder 202 andcorrect the position of the substrate holder 202 such that the targetportion C is at a correct position beneath the projection system PSduring exposure. An example of such a control unit, which can be used inthe context of the invention, is disclosed in Japanese patentapplication publication No. JP 2002-353121 A, hereby incorporated byreference.

Additionally or alternatively, based on the measurement informationand/or the further measurement information, the control unit may controlan optical property of an aerial image, an optical property of theprojection system PS, or both of these. For example, the control unitmay compensate for distortion of an image to be projected onto thesubstrate W, aberration of the projection system PS, and/or in-planedeformation of the substrate W by controlling one or both of theseoptical properties. These optical properties that the control unitcontrols may be magnification-X (i.e., magnification along the x-axis orin the stepping direction), magnification-Y (i.e., magnification alongthe y-axis or in the scanning direction), distortion, coma, fieldcurvature, spherical aberration and/or astigmatism. One or some of theseoptical properties may be controlled by actuating the position and/ororientation of optical elements (in the projection system PS) duringexposure, during scanning and/or during stepping. An example of such acontrol unit, which can be used in the context of the invention, isdisclosed in Japanese patent application publication No. JP2007-012673A, hereby incorporated by reference.

The control unit may use the fine wafer alignment information asprovided by the measurement device 220 to determine an accuratealignment correction (or a distortion map). The accurate alignmentcorrection (or the distortion map) may have linear components (orlow-order components) and higher-order components to define the actualshape of the substrate W compared to a nominal shape. These componentsof the distortion map may be mathematically expressed in terms ofcoefficients of a polynomial. For example, the fine wafer alignmentinformation is based on an alignment mark at every target portion C oris based on a plurality of alignment marks at every target portion C(e.g., the substrate alignment marks P1, P2). A deformation ordistortion of the substrate W within a target portion C (i.e., within anexposure field or within a die) may be referred to as an intra-fielddistortion. An overlay error at least partially induced by theintra-field distortion may be referred to as an intra-field overlayerror. A deformation or distortion of the substrate W between dies orexposure fields may be referred to as an inter-field distortion. Anoverlay error at least partially induced by the inter-field distortionmay be referred to as an inter-field overlay error. In an embodiment,the number of these alignment marks is less than the number of exposurefields (or the number of dies). Alternatively, the number of thesealignment marks equals the number of exposure fields (or the number ofdies). A deformation of the substrate W, such as bending or warping orstretching, results in a displacement of the alignment marks relative toeach other. Based on the fine alignment information, the control unitmay accurately determine the actual shape of the substrate W. Themeasurement device 220 may provide the fine wafer alignment informationbased on overlay marks, which may be located in a target portion C,and/or based on substrate alignment marks P1, P2, which may be locatedin between the target portions C. In an embodiment, the fine waferalignment information, which contains information of a deformation ofthe substrate W, is based on the measurement of both overlay marks andsubstrate alignment marks. In an embodiment, the summation of numbers ofoverlay marks and/or substrate alignment marks on the substrate W, whichare measured by the measurement device 220, is greater than or equal tothe number of exposure fields (or the number of dies); e.g., if thereare 96 exposure fields (or dies) on the substrate W, the summation ofnumbers of overlay marks and/or substrate alignment marks on thesubstrate W, which are measured by the measurement device 220, may begreater than or equal to 96. In general, wafer alignment informationthat is based on measurements of a larger number of marks (e.g.,substrate alignment marks and/or overlay marks on the substrate W)enables to more accurately determine the actual shape of the substrateW. Hence, when the measurement device 220 measures a large number ofmarks on the substrate W, the imaging quality of the lithographicapparatus may increase (or may be improved).

When the movement device 230 transports the first substrate W1L1 fromthe further substrate holder 702 to the substrate holder 202, the actualshape of the substrate W may change into a new actual shape. However,the difference between the actual shape and the new actual shapetypically has only low spatial frequencies. Based on a small number ofmeasurements of substrate alignment marks, the further measurementdevice 950 may provide the coarse alignment information. The smallnumber may be in a range of 3-20, for example 16. Based on the coarsealignment information and on the fine alignment information, the controlunit may determine the new shape of the substrate W. Because the controlunit is able to determine the new shape of the substrate W in this way,the imaging quality of the lithographic apparatus may increase (or maybe improved), and/or better overall productivity can be achieved whilesimultaneously qualifying for a sufficient imaging quality required formanufacturing ICs.

The fine wafer alignment information as provided by the measurementdevice 220 may be implemented as a fine distortion map, i.e., a map ofthe surface of the substrate W indicating the amount of distortion witha large detail. The coarse wafer alignment information as provided bythe further measurement device 950 may be implemented as a coarsedistortion map, i.e., a map of the surface of the substrate W indicatingthe amount of distortion with less detail. The control unit may combine(or synthesize) the fine distortion map and the coarse distortion map tocreate a combined distortion map, which may also be referred to as acomposite distortion map or an integrated distortion map. Based on thecombined distortion map, the control unit may control the position ofthe substrate holder 202. Additionally or alternatively, the controlunit may create a combined distortion map for each substrate in a lot(or for some substrates in a lot). For example, the control unit maycreate a first combined distortion map for the first substrate W1L1 bycombining (or synthesizing) a first fine distortion map and a firstcoarse distortion map, which are maps of the surface of the firstsubstrate W1L1. Similarly, the control unit may create a second combineddistortion map for the second substrate W2L1 by combining (orsynthesizing) a second fine distortion map and a second coarsedistortion map, which are maps of the surface of the second substrateW2L1. Alternatively, the control unit may create a second combineddistortion map for any one of the other substrates in the lot, based onthe fine distortion map and the coarse distortion map of the substrate.Additionally or alternatively, the control unit may create a thirdcombined distortion map for one of the other substrates in a second lot,based on the fine distortion map and the coarse distortion map of thesubstrate in the second lot.

Additionally or alternatively, based on a fine distortion map and/or acombined distortion map, the control unit may control an opticalproperty of an aerial image, an optical property of the projectionsystem PS, or both of these. Based on the fine distortion map, and/orbased on the combined distortion map, and/or based on measurement dataof one of the sensors that the sensor holder 206 holds, and/or based ona simulation model, the control unit may compensate for distortion of animage to be projected onto the substrate W, aberration of the projectionsystem PS, and/or in-plane deformation of the substrate W. Themeasurement data, obtained by one of the sensors that the sensor holder206 holds, may include a property of the projection system PS, aproperty of an aerial image, and/or a property of the exposure beam. Thecontrol unit may control one or some of the following optical propertiesof an aerial image and/or the projection system PS: magnification-X,magnification-Y, distortion, coma, field curvature, sphericalaberration, astigmatism, or any other types of aberrations.

One or some of these optical properties of an aerial image and/or theprojection system PS may be controlled by actuating the position and/ororientation of optical elements (with respect to the lens barrel, withrespect to the path of the radiation beam B, or with respect to theoptical axis of the projection system PS) during exposure, duringscanning and/or during stepping. One or more of these optical elementsin the projection system PS may be supported by a lens holder and/or maybe actively actuated (or controlled) by piezo-actuators during exposureand/or during a scan.

One or some of these optical properties of an aerial image and/or theprojection system PS may be actively controlled by a deformable mirrorin the projection system PS. An example of such a deformable mirror,which can be used in the context of the invention, is disclosed inJapanese patent application publication No. JP 2013-161992A, herebyincorporated by reference.

At least one of the optical properties of an aerial image may becontrolled by bending the patterning device MA and/or by controlling theposition of the substrate holder 202. In an embodiment, field curvatureis at least partially compensated by bending the patterning device MA.Additionally or alternatively, inter-field overlay errors and/orlow-order components of intra-field overlay errors are at leastpartially compensated by controlling the position of the substrateholder 202 during exposure. With these compensations, better imagingquality would be achieved; in other words, better overall productivitywould be achieved while simultaneously qualifying for a sufficientimaging quality required for manufacturing ICs.

In an embodiment, the control unit creates a combined distortion map bycombining (or synthesizing) a fine distortion map and a coarsedistortion map, both of which contain information about in-planedeformation of the substrate W. Additionally or alternatively, based onthe fine distortion map and/or the combined distortion map, the controlunit compensates for in-plane deformation of the substrate W bycontrolling the position of the substrate holder 202, an opticalproperty of an aerial image, and/or an optical property of theprojection system PS. By operating the lithographic apparatus in such away, a certain imaging quality requirement (e.g., an overlayrequirement), e.g. for a specific node, can be satisfied. In contrast,when compensating for in-plane deformation of the substrate W, based onthe coarse distortion map only, the same certain imaging qualityrequirement may not be satisfied,

In an embodiment, a fine distortion map and/or a combined distortion mapmay be used to calibrate, update and/or improve a simulation model thatpredicts an aerial image and/or a pattern created on the substrate.Additionally or alternatively, multiple fine distortion maps and/ormultiple combined distortion maps may be used to calibrate, updateand/or improve a simulation model. For example, a first fine distortionmap (and/or a first combined distortion map), which provides informationabout in-plane deformation of the first substrate W1L1, and a secondfine distortion map (and/or a second combined distortion map), whichprovides information about in-plane deformation of the second substrateW2L1, may be used as a set of measurement data obtained at differentpoints of time during operation of an exposure apparatus for exposing alot of wafers. This set of measurement data may be used to calibrate,update and/or improve a simulation model that predicts an aerial imageand/or a pattern created on the substrate as a function of time. Forexample, such a simulation model may predict how an aerial image (and/ora pattern created on the substrate) is affected by temperature changes(over time) of the patterning device MA, optical elements in theprojection system PS, and/or the substrate holder 202. Comparing the setof simulations and the set of measurement data obtained at differentpoints of time, the accuracy of the simulation model may be improved. Inaddition to these multiple fine distortion maps (and/or multiplecombined distortion maps), other types of measurement data (such astemperature of purging gas, the patterning device MA, optical elementsin the projection system PS, and/or the substrate holder 202) may beused to calibrate, update and/or improve the simulation model. If asimulation model can be calibrated, updated and/or improved based onmeasurement data obtained during production of ICs (i.e., during anuptime of an exposure apparatus), better overall productivity can beachieved comparing to a method of calibrating, updating and/or improvingthe simulation model that is based on an offline test exposure using atest reticle (i.e., during a downtime of an exposure apparatus).

Aberrations may be described in terms of the Zernike polynomials.Aberrations may be described in terms of a set of trigonometricfunctions. Types of aberrations may be categorized into odd-ordercomponents and even-order components, e.g., based on the characteristicsof the Zernike polynomials and/or the set of trigonometric functions.For example, Zernike terms described by a sine function may be referredto as odd-order components. Zernike terms described by a cosine functionmay be referred to as even-order components. Aberrations caused by atemperature change (e.g., heating or cooling) of optical elements in theprojection system PS may be referred to as thermal aberrations.

In an embodiment, at least one of the even-order components ofaberrations is controlled by a deformable mirror in the projectionsystem PS. Additionally or alternatively, at least one of the odd-ordercomponents of aberrations is controlled by a deformable mirror in theprojection system PS. Additionally or alternatively, thermal aberrationsare at least partially compensated by a deformable mirror in theprojection system PS. Additionally or alternatively, at least one of theodd-order components of aberrations is controlled by actuating theposition and/or orientation of optical elements (with respect to thelens barrel, with respect to the path of the radiation beam B, or withrespect to the optical axis of the projection system PS) duringexposure, during scanning and/or during stepping. By operating thelithographic apparatus in such a way, better imaging quality can beachieved.

The movement device 230 may be arranged to transports the substrate Wfrom the further substrate holder 702 to the substrate holder 202. Themovement device 230 may comprise a robotic arm and/or a wafer handler.The movement device 230 may comprise a gripper to contact a bottom sideof the substrate W. The movement device 230 may comprise a Bernouillichuck to hold of the substrate W at the top surface of the substrate W.An gas film between the top surface of the substrate W and theBernouilli chuck prevents physical contact between the substrate W andthe Bernouilli chuck. A Bernoulli chuck is described in thePCT-application publication No. WO 2013/100203A2, hereby incorporated byreference. Part of the movement device 230 may be implemented as liftingpins to lift the substrate W from the substrate holder 202. The liftingpins may lift the substrate W from the substrate holder 202 far enoughto provide a space between the substrate W and the substrate holder 202,such that the movement device 230 can provide a gripper beneath thesubstrate W to lift the substrate W from the lifting pins.

In an embodiment, the lithographic apparatus may comprise a liquidhandling system configured to supply and confine the immersion liquid toa space defined between the projection system PS and at least one of thesubstrate holder 202, the substrate W, and the sensor holder 206. Alithographic apparatus that comprises a liquid handling system may bereferred to as an immersion lithographic apparatus, an immersionexposure apparatus, or an immersion scanner. When the sensor holder 206is located beneath the projection system PS as depicted in FIG. 10C, theliquid handling system may supply and confine the immersion liquid tothe space defined between the projection system PS and the sensor holder206. At a different point of time during operation of the immersionexposure apparatus, e.g., during exposure, when the substrate holder 202is located beneath the projection system PS as depicted in FIG. 9 andFIG. 10D, the liquid handling system may supply and confine theimmersion liquid to the space defined between the projection system PSand the substrate W (and/or to the space defined between the projectionsystem PS and the substrate holder 202).

In an embodiment, the liquid handling system comprises a supply port,which is capable of supplying the immersion liquid to the space definedbetween the projection system PS and the substrate W (or defined betweenthe projection system PS and the substrate holder 202, or definedbetween the projection system PS and the sensor holder 206). The liquidhandling system further comprises a recovery port, which is capable ofrecovering the liquid from the space. A porous member, which has aplurality of holes (i.e., openings or pores), may be disposed in therecovery port. The porous member may, e.g., be a mesh plate whereinnumerous small holes are formed in a mesh. An example of such a liquidhandling system is disclosed in the PCT-application publication No. WO2010/018825A1, which is hereby incorporated by reference in itsentirety.

Additionally or alternatively, the liquid handling system comprises anactuatable flow plate, which is configured to be independentlyposition-controlled with respect to the projection system PS and/or withrespect to the substrate holder 202. In general, there can be atrade-off between a higher speed/acceleration (of the stepping and/orscanning motions of the substrate holder 202) and a stability ofmeniscus of the confined immersion liquid. In other words, the higherspeed/acceleration of the stepping and/or scanning motions of thesubstrate holder 202 improves a throughput performance of the immersionexposure apparatus, but it also means that the relativevelocity/acceleration between the liquid handling system and thesubstrate W (and/or the substrate holder 202) are higher. The higherrelative velocity/acceleration can make the meniscus more unstable;furthermore, unstable meniscus can cause defect problems such as leakageof the immersion liquid and generation of droplets on the surface of thesubstrate holder 202, the substrate W, and/or the sensor holder 206.These defect problems can deteriorate the uptime performance of theimmersion exposure apparatus. In case these defect problems areprevented by reducing the speed/acceleration of the stepping and/orscanning motions of the substrate holder 202 (i.e., by exposing thesubstrate W at a lower scan speed, scan acceleration, and steppingacceleration), the throughput performance of the immersion exposureapparatus will be deteriorated. Hence, this trade-off can also berecognized as a trade-off between a throughput performance and an uptimeperformance, which deteriorates an overall productivity of the immersionexposure apparatus. In order to prevent these potential defect problems,the control unit may drive (or control a position of) the substrateholder 202 and/or the actuatable flow plate to reduce the relativevelocity and acceleration between the actuatable flow plate and thesubstrate W (and/or the substrate holder 202). By controlling thesubstrate holder 202 and/or the actuatable flow plate such a manner(i.e., by reducing the relative velocity/acceleration between theactuatable flow plate and the substrate W without reducing the scanspeed, scan acceleration, and/or stepping acceleration), leakage of theimmersion liquid during exposure (during the stepping and/or scanningmotions of the substrate holder 202) may be prevented, and/or it may beensured that the immersion liquid remains confined in the space definedbetween the projection system PS and the substrate W (and/or in thespace defined between the projection system PS and the substrate holder202). Therefore, better overall productivity can be achieved. An exampleof a liquid handling system, which can be used in the context of thisembodiment, is disclosed in Japanese patent application publication No.JP 2014-120693A, which is hereby incorporated by reference in itsentirety.

In an embodiment, the substrate holder 202 and the sensor holder 206 maybe arranged to move in unison in order to transfer the immersion liquidfrom the substrate holder 202 (and/or the substrate W) to the sensorholder 206 (and vice versa). During the move in unison, the substrateholder 202 and the sensor holder 206 may be in contact with each otheror separated from each other by a gap that is sufficiently small toprevent leakage of the immersion liquid.

In an embodiment, each of the substrate holder 202 and the sensor holder206 has its own mover 204. The substrate holder 202 has a mover to movethe substrate holder 202 relative to the projection system PS. Thesensor holder 206 has a further mover to move the sensor holder 206relative to the projection system PS. The mover and/or the further movermay comprise a planar motor to move on both the x-direction and they-direction. The planar motor may be a moving magnet type planar motor,which has magnets and electrical coils. The magnets may be arranged onthe substrate holder 202 and/or on the sensor holder 206, whereas theelectrical coils are stationary. Additionally or alternatively, thefurther mover may comprise two stacked linear motors and may be arrangedin an H-drive-arrangement. In an embodiment, the substrate holder 202and the other substrate holder 212 are each moved by a planar motor,whereas the sensor holder 206 is moved by two stacked linear motors andmay be arranged in an H-drive-arrangement. In an embodiment, thesubstrate holder 202, the other substrate holder 212 and the sensorholder 206 are each moved by linear motors arranged in anH-drive-arrangement.

Although specific reference may be made in this text to the use oflithographic apparatus in the manufacture of ICs, it should beunderstood that the lithographic apparatus described herein may haveother applications, such as the manufacture of integrated opticalsystems, guidance and detection patterns for magnetic domain memories,flat-panel displays, liquid-crystal displays (LCDs), thin-film magneticheads, etc. The skilled artisan will appreciate that, in the context ofsuch alternative applications, any use of the terms “wafer” or “die”herein may be considered as synonymous with the more general terms“substrate” or “target portion”, respectively. The substrate W referredto herein may be processed, before or after exposure, in for example atrack (a tool that typically applies a layer of resist to a substrateand develops the exposed resist), a metrology tool and/or an inspectiontool. Where applicable, the disclosure herein may be applied to such andother substrate processing tools. Further, the substrate W may beprocessed more than once, for example in order to create a multi-layerIC, so that the term substrate W used herein may also refer to asubstrate that already contains multiple processed layers.

Although specific reference may have been made above to the use ofembodiments of the invention in the context of optical lithography, itwill be appreciated that the invention may be used in otherapplications, for example imprint lithography and e-beam lithography,and where the context allows, is not limited to optical lithography. Inimprint lithography a topography in a patterning device MA defines thepattern created on a substrate. The topography of the patterning devicemay be pressed into a layer of resist supplied to the substratewhereupon the resist is cured by applying electromagnetic radiation,heat, pressure or a combination thereof. The patterning device MA ismoved out of the resist leaving a pattern in it after the resist iscured.

While specific embodiments of the invention have been described above,it will be appreciated that the invention may be practiced otherwisethan as described. For example, the invention may take the form of acomputer program containing one or more sequences of machine-readableinstructions describing a method as disclosed above, or a data storagemedium (e.g. semiconductor memory, magnetic or optical disk) having sucha computer program stored therein.

The descriptions above are intended to be illustrative, not limiting.Thus, it will be apparent to one skilled in the art that modificationsmay be made to the invention as described without departing from thescope of the claims set out below. Other aspects of the invention areset out as in the following numbered clauses:

-   1. An exposure apparatus comprising;    -   a substrate holder for holding a substrate;    -   a sensor holder for holding a sensor; and    -   a mover arranged for moving the substrate holder    -   wherein the mover is arranged to couple with the sensor holder        in a first situation so as to move the sensor holder,    -   wherein the mover is arranged to decouple from the sensor holder        in a second situation so as to move without moving the sensor        holder.-   2. The exposure apparatus of clause 1, comprising an exchange    mechanism for providing the sensor holder to the mover and for    removing the sensor holder from the mover.-   3. The exposure apparatus of clause 1 or 2, wherein the mover is    arranged to move a further substrate holder for holding a further    substrate, wherein a size of the further substrate is different from    a size of the substrate.-   4. The exposure apparatus of clause 3, wherein the sensor holder has    a length and a width, wherein the length substantially equals a size    of the substrate holder, wherein the width substantially equals a    size of the further substrate holder, wherein the length and the    width are different from each other.-   5. The exposure apparatus of clause 3 or 4, wherein the mover is    arranged to support the sensor holder in a first orientation and in    a second orientation,    -   wherein, in the first orientation, the sensor holder has a first        angle along an axis perpendicular to a horizontal plane,    -   wherein, in the second orientation, the sensor holder has a        second angle along the axis perpendicular to the horizontal        plane,    -   wherein the first angle is different from the second angle.-   6. The exposure apparatus of one of the preceding clauses, wherein    the substrate holder and the sensor holder are arranged to move in    unison relative to the mover in the first situation.-   7. The exposure apparatus of clause 6, comprising a nozzle for    providing a liquid to one of a top surface of the substrate holder    and a top surface of the sensor holder, wherein the exposure    apparatus is arranged to transfer the liquid from the one of the top    surface of the substrate holder and the top surface of the sensor    holder to the other of the top surface of the substrate holder and    the top surface of the sensor holder while the substrate holder and    the sensor holder move in unison relative to the mover.-   8. The exposure apparatus of one of clauses 1-5, wherein the mover    is arranged to decouple with the substrate holder in the first    situation so as to move without moving the substrate holder.-   9. The exposure apparatus of one of the preceding clauses, wherein    the sensor holder is arranged to receive a radiation beam from the    substrate holder.-   10. The exposure apparatus of clause 9, wherein the substrate holder    comprises a marker, wherein the radiation beam comprises information    about an image projected on the marker.-   11. The exposure apparatus of clause 9 or 10, wherein the sensor    holder is arranged to propagate the radiation beam to a detector,    wherein the sensor holder is movable relative to the detector.-   12. The exposure apparatus of one of the preceding clauses,    comprising an exposure device and a measurement device, wherein the    exposure device is arranged to expose the substrate with an exposure    beam, wherein the measurement device is arranged to provide    measurement information of the substrate, wherein the exposure    device and the measurement device are distant to each other, wherein    the mover is arranged to support the substrate holder while near the    exposure device.-   13. The exposure apparatus of clause 12, comprising a stationary    support arranged to support the substrate holder while near the    measurement device.-   14. The exposure apparatus of clause 13, comprising a first encoder    head and a first scale, wherein the stationary support comprises a    recess for holding the first encoder head, wherein the first scale    is arranged at a bottom surface of the substrate holder, wherein the    first encoder head faces the first scale while the substrate holder    is near the measurement device and is arranged to provide a signal    representative of positional information of the substrate holder.-   15. The exposure apparatus of clause 14, wherein the first encoder    head is coupled to the stationary support via a dynamical isolator.-   16. The exposure apparatus of one of clauses 12-15, comprising a    movement device arranged to move the substrate holder while    supported by the stationary support.-   17. The exposure apparatus of one of clauses 12-16, comprising a    frame for supporting the exposure device, wherein the exposure    device is movable relative to the frame.-   18. The exposure apparatus of one of clauses 12-17, comprising a    further measurement device arranged to provide further measurement    information of the substrate, wherein the further measurement device    is closer to the exposure device than the measurement device.-   19. The exposure apparatus of one of the preceding clauses,    comprising a second encoder, wherein the second encoder head is    arranged to face the first scale so as to provide a second signal    representative of positional information of the substrate holder.-   20. The exposure apparatus of one of the preceding clauses,    comprising a third encoder head and a third scale, wherein the third    scale is arranged at a bottom side of the sensor holder, wherein the    third encoder head is arranged to face the third scale, so as to    provide a third signal representative of positional information of    the sensor holder.-   21. An exposure apparatus comprising;    -   a substrate holder for holding a substrate;    -   a sensor holder for holding a sensor;    -   a mover arranged for moving the substrate holder; and    -   a projection system arranged to provide a beam of radiation onto        the substrate,    -   wherein during exposure, the projection system provides the beam        of radiation onto the substrate when the sensor holder is        decoupled from the mover,    -   wherein the mover couples with the sensor holder when the sensor        measures a property of the projection system or the radiation        beam.-   22. The exposure apparatus of clause 21, comprising an exchange    mechanism for providing the sensor holder to the mover and for    removing the sensor holder from the mover.-   23. The exposure apparatus of clause 21 or 22, wherein the mover is    arranged to move a further substrate holder for holding a further    substrate, wherein a size of the further substrate is different from    a size of the substrate.-   24. The exposure apparatus of clause 23, wherein the sensor holder    has a length and a width, wherein the length substantially equals a    size of the substrate holder, wherein the width substantially equals    a size of the further substrate holder, wherein the length and the    width are different from each other.-   25. The exposure apparatus of clause 23 or 24, wherein the mover is    arranged to support the sensor holder in a first orientation and in    a second orientation,    -   wherein, in the first orientation, the sensor holder has a first        angle along an axis perpendicular to a horizontal plane,    -   wherein, in the second orientation, the sensor holder has a        second angle along the axis perpendicular to the horizontal        plane,    -   wherein the first angle is different from the second angle.-   26. The exposure apparatus of one of clauses 21-25, wherein the    mover is arranged to decouple from the substrate holder so as to    move without moving the substrate holder.-   27. The exposure apparatus of one of clauses 21-26, wherein the    sensor holder is arranged to receive the radiation beam from the    substrate holder.-   28, The exposure apparatus of clauses 27, wherein the substrate    holder comprises a marker, wherein the radiation beam comprises    information about an image projected on the marker.-   29. The exposure apparatus of clauses 27 or 28, wherein the sensor    holder is arranged to propagate the radiation beam to a detector,    wherein the sensor holder is movable relative to the detector.-   30. The exposure apparatus of one clauses 21-29, comprising an    exposure device and a measurement device, wherein the exposure    device is arranged to expose the substrate with an exposure beam,    wherein the measurement device is arranged to provide measurement    information of the substrate, wherein the exposure device and the    measurement device are distant to each other, wherein the mover is    arranged to support the substrate holder while near the exposure    device.-   31. The exposure apparatus of clause 30, comprising a stationary    support arranged to support the substrate holder while near the    measurement device.-   32. The exposure apparatus of clause 31, comprising a first encoder    head and a first scale, wherein the stationary support comprises a    recess for holding the first encoder head, wherein the first scale    is arranged at a bottom surface of the substrate holder, wherein the    first encoder head faces the first scale while the substrate holder    is near the measurement device and is arranged to provide a signal    representative of positional information of the substrate holder.-   33. The exposure apparatus of clause 32, wherein the first encoder    head is coupled to the stationary support via a dynamical isolator.-   34. The exposure apparatus of one of clauses 31-33, comprising a    movement device arranged to move the substrate holder while    supported by the stationary support.-   35. The exposure apparatus of one of clauses 31-34, comprising a    frame for supporting the exposure device, wherein the exposure    device is movable relative to the frame.-   36. The exposure apparatus of one of clauses 31-35, comprising a    further measurement device arranged to provide further measurement    information of the substrate, wherein the further measurement device    is closer to the exposure device than the measurement device.-   37. The exposure apparatus of one of clauses 31-36, comprising a    second encoder head, wherein the second encoder head is arranged to    face the first scale so as to provide a second signal representative    of positional information of the substrate holder.-   38. The exposure apparatus of one of clauses 31-37, comprising a    third encoder head and a third scale, wherein the third scale is    arranged at a bottom side of the sensor holder, wherein the third    encoder head is arrange to face the third scale, so as to provide a    third signal representative of positional information of the sensor    holder.-   39. An exposure apparatus comprising:    -   a first substrate holder for holding a first substrate;    -   a second substrate holder for holding a second substrate;    -   a projection system for exposing the first substrate with an        exposure beam;    -   a measurement device arranged to provide measurement information        of the second substrate;    -   a further measurement device arranged to provide measurement        information of the first substrate,    -   wherein the further measurement device is closer to the        projection system than the measurement device.-   40. The exposure apparatus of clause 39, wherein the further    measurement information of the first substrate comprises a height    profile and/or an in-plane deformation of the first substrate.-   41. The exposure apparatus of clauses 39-40, wherein the measurement    device is configured to provide information about the positions of    substrate alignment marks on the second substrate.-   42. The exposure apparatus of one of clauses 39-41, comprising a    sensor holder for holding a sensor, and    -   a mover for moving the substrate holder relative to the        projection system,    -   wherein the sensor is arranged to measure a property of the        exposure beam or the projection system.-   43. The exposure apparatus of clause 42, wherein the further    measurement device is arranged to acquire the measurement    information of the first substrate while the sensor is measuring the    property of the exposure beam.-   44. The exposure apparatus of one clauses 39-43, the lithographic    apparatus is arranged to transport the first substrate from the    first substrate holder to the second substrate holder, wherein the    measurement device arranged to provide measurement information of    the first substrate.-   45. The exposure apparatus of one of clauses 39-44, wherein the    measurement device is arranged to acquire the measurement    information of the second substrate when the second substrate holder    is at the first position, wherein the further measurement device is    arranged to acquire the measurement information of the second    substrate when the second substrate holder is at the second    position.-   46. The exposure apparatus of one of clauses 39-45, wherein the    further measurement device is arranged propagate a plurality of    measurement beams on the first substrate simultaneously.-   47. The exposure apparatus of one of clauses 3946, comprising a    control unit arranged to drive the first substrate holder and the    second substrate holder based on the measurement information of the    first substrate and measurement information of the second substrate.-   48. The exposure apparatus of one of clauses 39-47, wherein the    first substrate is provided with a first alignment mark, wherein the    further measurement device is arranged to provide the measurement    information of the first substrate based on a position of the second    alignment mark.-   49. The exposure apparatus of one of clauses 39-48, wherein the    second substrate is provided with a second alignment mark, wherein    the measurement device is arranged to provide the measurement    information of the second substrate based on a position of the    second alignment mark.

Other aspects of the invention are described in the following numberedclauses:

-   50. An exposure apparatus comprising:    -   a first substrate holder configured to hold a substrate;    -   a second substrate holder configured to hold the substrate;    -   a sensor holder configured to hold a sensor,    -   a projection system configured to expose the substrate with an        exposure beam;    -   a measurement device configured to provide measurement        information of the substrate;    -   a further measurement device configured to provide further        measurement information of the substrate,    -   wherein the sensor is configured to measure a property of the        exposure beam and/or the projection system,    -   wherein the projection system is configured to expose the sensor        with the exposure beam.-   51. The exposure apparatus of clause 50, wherein the exposure    apparatus is arranged to hold the substrate on the first substrate    holder while the measurement device is acquiring the measurement    information of the substrate, and wherein the exposure apparatus is    arranged to hold the substrate on the second substrate holder while    the further measurement device is acquiring the further measurement    information of the substrate.-   52. The exposure apparatus according to clause 50 or clause 51,    wherein at least one of the measurement device and the further    measurement device is configured to provide information about a    deformation of the substrate.-   53. The exposure apparatus according to any of clauses 50 to 52,    wherein the measurement device is located further away from the    projection system than the further measurement device.-   54. The exposure apparatus according to any of clauses 50 to 53,    wherein the further measurement device comprises a levelling sensor    system configured to provide a beam of radiation at a sianted angle    with the substrate and configured to provide information about a    flatness of the substrate.-   55. The exposure apparatus according to any of clauses 50 to 54,    wherein at least one of the measurement device and the further    measurement device comprises an alignment sensor configured to    measure positions of substrate alignment marks on the substrate.-   56. The exposure apparatus according to clause 55, wherein the    measurement device is configured to provide fine alignment    information based on measurement of the substrate alignment marks,    -   wherein the further measurement device is configured to provide        coarse alignment information based on measurements of the        substrate alignment marks,    -   wherein the exposure apparatus comprises a control unit        configured to create a fine distortion map based on the fine        alignment information, to create a coarse distortion map based        on the coarse alignment information, and to create a combined        distortion map by combining the fine distortion map and the        coarse distortion map.-   57. The exposure apparatus according to clause 56, comprising a    simulation model configured to predict a pattern created on the    substrate by the exposure beam, wherein the control unit is    configured to calibrate or update the simulation model, based on the    fine distortion map and/or the combined distortion map.-   58. The exposure apparatus according to clause 56 or clause 57,    wherein the control unit is configured to control an optical    property of the projection system, based on the fine distortion map    and/or the combined distortion map.-   59. The exposure apparatus according to any of clauses 50 to 58,    wherein the exposure apparatus comprises:    -   a support structure configured to hold a patterning device,        wherein the patterning device is configured to impart a pattern        into the exposure beam so as to image the pattern onto the        substrate,    -   wherein the support structure is configured to actively bend the        patterning device.-   60. The exposure apparatus according to any of clauses 50 to 59,    wherein the projection system comprises:    -   a lens barrel;    -   an optical element; and    -   a lens holder configured to hold the optical element,    -   wherein the lens holder comprises an actuator to control the        position and/or orientation of the optical element with respect        to the lens barrel.-   61. The exposure apparatus according to any of clauses 50 to 60,    comprising a liquid handling system configured to supply and confine    immersion liquid to a space defined between the projection system    and at least one of the first substrate holder, the second substrate    holder, the substrate, and the sensor holder.-   62. The exposure apparatus according to clause 61, wherein the    liquid handling system comprises a recovery port configured to    recover the immersion liquid from the space, wherein a porous member    is disposed in the recovery port.-   63. The exposure apparatus according to any of clauses 50 to 62,    wherein the projection system comprises a deformable mirror.-   64. The exposure apparatus according to any of clauses 50 to 63,    wherein the property of the exposure beam is at least one of a dose,    an aberration and an uniformity.

What is claimed is:
 1. An exposure apparatus arranged to project aradiation beam onto a target portion of a substrate, the exposureapparatus comprising: a first substrate holder configured to hold thesubstrate; a second substrate holder configured to hold the substrate; asensor holder configured to hold a sensor and/or detector; a firstmeasurement device comprising a first alignment system comprising analignment sensor configured to measure positions of a substratealignment mark on the substrate; a second measurement device comprisinga second alignment system comprising a further alignment sensorconfigured to measure positions of the substrate alignment mark on thesubstrate, wherein the second alignment system is arranged to measurethe substrate while the first alignment system measures anothersubstrate; a first scale arranged on a lower surface of the firstsubstrate holder; and a first encoder head arranged to cooperate withthe first scale, the first encoder head arranged to be located beneaththe first alignment system and held by a stationary support.
 2. Theapparatus of claim 1, further comprising: a single illumination systemconfigured to condition the radiation beam; and a single projectionsystem configured to project a pattern imparted to the radiation beam bya patterning device onto the target portion of the substrate.
 3. Theapparatus of claim 2, wherein the first measurement device is locatedfurther away from the single projection system than the secondmeasurement device.
 4. The apparatus of claim 2, further comprising aposition measurement system having an encoder head system comprisingmultiple encoder heads, capacitive sensors and/or interferometricsensors, wherein the encoder head system is located closer to the singleprojection system and the second measurement device than the firstmeasurement device, and wherein the position measurement system isarranged to provide a signal representative of positional information ofthe second substrate holder and/or the sensor holder while the secondsubstrate holder and/or the sensor holder is/are located near or at thesingle projection system.
 5. The apparatus of claim 2, furthercomprising a control unit configured to: implement desired calculationsrelevant to the operation of the exposure; process multiple signals;execute an algorithm; control a position of the second substrate holder;control an optical property of an aerial image; and/or control anoptical property of the single projection system, wherein the singleprojection system comprises a lens barrel, an optical element, and aholder configured to hold the optical element, and wherein the controlunit is configured to compensate for inter-field overlay errors and/orintra-field overlay errors, based on a fine distortion map and/or acombined distortion map, by controlling: a position of the secondsubstrate holder, an optical property of the aerial image, an opticalproperty of the single projection system, and/or a position and/ororientation of the optical element with respect to the lens barrel. 6.The apparatus of claim 2, further comprising a liquid handling systemconfigured to supply and confine immersion liquid to a space definedbetween the single projection system and at least one selected from: thesecond substrate holder, the substrate, and/or the sensor holder.
 7. Anapparatus for an exposure tool arranged to project a radiation beam ontoa target portion of a substrate, the apparatus comprising: a firstsubstrate holder configured to hold the substrate; a second substrateholder configured to hold the substrate; a sensor holder configured tohold a sensor and/or detector; a first measurement device comprising afirst alignment system comprising an alignment sensor configured tomeasure positions of a substrate alignment mark on the substrate; asecond measurement device comprising a second alignment systemcomprising a further alignment sensor configured to measure positions ofthe substrate alignment mark on the substrate, wherein the secondalignment system is arranged to measure the substrate while the firstalignment system measures another substrate; a first scale arranged on alower surface of the first substrate holder; and a first encoder headarranged to cooperate with the first scale, the first encoder headarranged to be located beneath the first alignment system and held by astationary support.
 8. The apparatus of claim 7, comprising a firstposition measurement system having the first encoder head and the firstscale, the first position measurement system configured to provide afirst signal representative of positional information of the firstsubstrate holder while the first substrate holder is near or at thefirst measurement device.
 9. The apparatus of claim 7, configured tohold the substrate on the first substrate holder while the firstalignment system is measuring positions of the substrate alignment markon the substrate, and configured to hold the substrate on the secondsubstrate holder while the second alignment system is measuringpositions of the substrate alignment mark on the substrate.
 10. Theapparatus of claim 7, configured such that the number of substratealignment marks measured by the second alignment system is between 3 and16.
 11. The apparatus of claim 7, configured such that the number ofsubstrate alignment marks measured by the first alignment system isgreater than or equal to a number of exposure fields on the substrate.12. The apparatus of claim 7, further comprising a movement deviceconfigured to transport the substrate from the first substrate holder tothe second substrate holder or vice versa.
 13. The apparatus of claim 7,wherein the sensor holder holds a wavefront aberration measuring device,an illuminance monitor, an illuminance irregularity sensor, a uniformitysensor and/or a sensor configured to measure polarization.
 14. Theapparatus of claim 7, configured to hold a further substrate on thefirst substrate holder, when the substrate is held by the secondsubstrate holder.
 15. The apparatus of claim 14, wherein the firstalignment system is configured to measure positions of a substratealignment mark of the further substrate during exposure of the substrateheld by the second substrate holder.
 16. The apparatus of claim 7,wherein the second alignment system comprises a plurality of alignmentsensors along a stepping direction that is perpendicular to apredetermined scanning direction of the exposure tool.
 17. The apparatusof claim 7, wherein the second alignment system comprises a plurality ofimage alignment sensors arranged to irradiate a broadband detection beamto the substrate alignment mark to detect an image of the substratealignment mark by an imaging device.
 18. The apparatus of claim 7,wherein the first alignment system comprises a single alignment sensor,and wherein the single alignment sensor is an image alignment sensorarranged to irradiate a broadband detection beam to the substratealignment mark to detect an image of the substrate alignment mark by animaging device.
 19. The apparatus of claim 7, wherein the secondmeasurement device comprises an auto-focus system.
 20. The apparatus ofclaim 19, wherein the auto-focus system comprises a radiation output toprovide a beam of radiation obliquely onto a top surface of thesubstrate, and is configured to provide information about a flatness ofthe substrate held by the second substrate holder based on reflectedradiation reflected by the top surface of the substrate.
 21. Theapparatus of claim 7, wherein the second substrate holder and the sensorholder are configured to move in unison before and/or after an exposureof the substrate.
 22. An apparatus for an exposure tool arranged toproject a radiation beam onto a target portion of a substrate, theapparatus comprising: a first substrate holder configured to hold thesubstrate; a second substrate holder configured to hold the substrate; asensor holder configured to hold a sensor and/or detector; a firstmeasurement device comprising a first alignment system comprising analignment sensor configured to measure positions of a substratealignment mark on the substrate; a second measurement device comprisinga second alignment system comprising a further alignment sensorconfigured to measure positions of the substrate alignment mark on thesubstrate; a first scale arranged on a lower surface of the firstsubstrate holder; and a first encoder head arranged to cooperate withthe first scale, the first encoder head arranged to be located beneaththe first alignment system and held by a stationary support, wherein theapparatus is configured to hold the substrate on the first substrateholder while the first alignment system is measuring positions of thesubstrate alignment mark on the substrate, and configured to hold thesubstrate on the second substrate holder while the second alignmentsystem is measuring positions of the substrate alignment mark on thesubstrate.